Term
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Definition
| Synthetic auxin. Membrane impermeable, requiring carrier-mediated active transport. Used as selective broadleaf herbicide. By itself it is not very toxic to humans, but is used to make Agent orange. Banned in certain areas of Ontario. There is no patent for it. Causes premature aging in the plant. Does not affect grasses. Some soybeans are resistant to it. If influx carriers are non-functional, then cells are resistant to 2,4-D. |
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Term
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Definition
| A three-carbon molecule. Two are produced in carboxylation of the Calvin-Benson cycle. |
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Term
| 3-phosphoglycerate kinase |
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Definition
Catalyzes the first reaction in reduction of the Calvin-Benson cycle.
3-phosphoglycerate + ATP → 1,3-bisphosphoglycerate + ADP |
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Term
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Definition
| Induces high levels of expression. |
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Term
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Definition
| A structure on the N-terminal half of phytochrome thought to be important for conversion from Pr to Pfr. |
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Term
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Definition
| The lower surface of the leaf. Transpirational water loss and gas exchange. Need to lose water from leaves to pull water from the roots, but too much water loss is bad for the plant. |
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Term
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Definition
| To kill and remove a cell, such as with a laser. |
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Term
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Definition
| Mutants of this gene in maize produce opposite phyllotaxy rather than alternate. Two ears can form at the same node. |
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Term
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Definition
| One of the Big 5. An important hormone involved in seed maturation, seed and bud dormancy, stomatal regulation, stomatal closure during environmental stress, senscence, vegetative growth, and response to pathogens. |
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Term
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Definition
| Plants that are paraistes of soil fungus. Lack chlorophyll. |
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Term
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Definition
| Movement of auxin away from the base of the plant. In the shoot, this is upwards. In the root, this is downwards. |
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Term
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Definition
| A CO2 molecule that activates rubisco. |
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Term
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Definition
| The upper surface of the leaf. Light harvesting. |
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Term
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Definition
| Roots which arise from the stem, rather than from the RAM. |
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Term
| Adventitious shoot meristem |
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Definition
| Rare shoot meristems which arise independently of the SAM. Produce shoots that form out of tree stumps, or when a plant is regenerated from a plant part, such as a leaf, rather than a seed. STM and CLV3 expression appears de novo. |
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Term
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Definition
| Plays a role in specifying the centre of the flower. Represses WUS. Unlike CLV3, it can continue expression even if WUS is removed. In ag mutants, WUS does not properly shut down in floral meristems. The floral meristem behaves like a shoot, and produces an indefinite number of floral parts. |
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Term
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Definition
| A component of MS medium. A solid support medium for roots to anchor the plant. |
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Term
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Definition
| Developed by the US military during the Vietnamese War. Contains 2,4-D as well as a carcinogenic compound. Was used as a weapon to defoliate forests. |
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Term
| Agrobacterium tumefaciens |
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Definition
Causes crown gall. A method to induce mutations. Used to randomly insert genes into pollen, embryo, or flower DNA. There are 2 - 3 insertions of large sequences. This can risrupt genes, causing aberrant or absent proteins, or alter gene expression. Mutation rate is 0.1% - 2.0%. Must screen 10,000+ plants to find 10 - 20 mutants. Better than EMA because you can screen out non-mutated plants with a resistance marker. Works best in dicots.
1. Expose M0 flowers to A. tumefaciens
2. Plant M1 mutagenized seeds
3. Harvest M2 seeds
4. Plant segregating M2 seeds
5. Screen for mutants |
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Term
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Definition
Catalyzes the second and fifth reaction of regeneration in the Calvin-Benson cycle.
2. glyceraldehyde 3-phosphate + dihydroxyacetone phosphate → fructose 1,6-bisphosphate
5. erythrose 4-phosphate + dihydroxyacetone phosphate → sedoheptulose 1,7-bisphosphate
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Term
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Definition
| A leaf phyllotaxy, where there is one leaf per node, alternating 180º each node. |
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Term
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Definition
| Mutants for this gene can have opposite phyllotaxy due to uncontrolled production of leaf meristems. Arabidopsis mutants produce 3 - 4 leaves per day, instead of the normal one. |
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Term
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Definition
| There is different vasculature in the roots than in the shoots. A transition occurs at the hypocotyl. |
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Term
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Definition
| Identified by molecular markers. Animal stem cells are much more versatile than originally thought. They can sometimes return to stem cells after differentiation. |
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Term
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Definition
| Cell walls form perpendicular to the tissue surface. Increases the number of cells in a cell layer. Elongates a cell file. |
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Term
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Definition
| The axis which runs between tips of the embryonic shoot and root. Develops in a plant due to environmental cues of gravity, light, and water. Gravity is the least important; plants may grow upside-down or in zero-gravity. |
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Term
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Definition
| One of the cells formed from the first division of the zygote. Shorter, and with a more dense cytoplasm than the basal cell. Produces nearly the entire embryo. Undergoes two longitudinal divisions then a set of transverse division to produce the octant. |
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Term
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Definition
| The top 4 cells of the octant. Gives rise to cotyledons and the SAM. |
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Term
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Definition
| Movement through the cell extracellular spaces. |
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Term
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Definition
| A transmembrane water cahnnel. Facilitates rapid transmembrane movement. |
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Term
| Arabidopsis Biological Resource Centre (ABRC) |
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Definition
| Provides seed stocks of Arabidopsis. |
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Term
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Definition
Mouse-ear cress
A small flowering winter annual weed popular for research in plants. A member of the Brassicaceae family. Has a small genome, about 125 Mb. Extensive genetic and physical maps are made of all 5 chromosomes. The first plant to have its genome completely sequenced, in 2000. There are 29,000 genes, but only a fraction have a described function. It has a rapid life cycle of about 6 weeks, and is self-pollinating, prolific, and easy to cultivate. The flower has four petals, four sepals, six stamens, and two carpels. It can be transgenically modified using A. tumefaciens. It has many mutant lines and genetic resources from a multinational research community: www.arabidopsis.org. Seed stocks are available from NASC or ABRC. |
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Term
| ASYMMETRIC LEAVES 1 (AS1) |
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Definition
| Expression is normally restricted to leaf primordia and primodium founder cells. Represses STM-related gene KNAT1. Encodes a transcription factor. Tells where leaves will form. In as1 mutants, KNAT1 expression persists in leaf primordia, resulting in leaves with shoot-like characteristics. Leaf-like organs form with no boundaries, no petioles, and messy-looking vasculature. The leaf cells are normal. |
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Term
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Definition
| Mutants have extremeley delayed and exaggerated gravitropism response to being placed sideways. Doesn't produce the correct amount of starch, so statoliths sediment much more slowly than normal. |
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Term
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Definition
| Energy is stored in the high-energy bond between ADP and Pi. |
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Term
| Epidermal cells that lack a trichome or a root hair. |
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Definition
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Term
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Definition
"To increase"
One of the Big 5. Can be chemically synthesized. A developmental hormone; the first plant hormone to be discovered. Involved in most growth movement, development of the quiescent centre, stem elongation, apical dominance, root initiation, fruit development, wound healing, leaf senescence, and tropic or oriented growth. Phototropism, gravitropism, and thigmotropism all depend on later distribution of auxin; differential cell elongation. Produced in all cells at a small level, but mostly at sites of active growth; action is short-lived. Gradients of this hormone tell plants where they are in the plant body, providing polarity. Response to auxin depends on concentration. Concentration level produces development in pre-programmed steps: the root emerges from the seed before the coleoptile as concentration increases. The only plant hormone that can be transported polarly as well as non-polarly. Polar auxin transport requires energy: mostly in non-vascular tissues, traveling cell to cell but not symplastically. Mutations which eliminate auxin are lethal. Includes IAA, NAA, and 2,4-D. |
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Term
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Definition
| When auxin moves out of a cell into the middle lamella. Found only on the basipetal side of the cell; establishes auxin transport pathway. Transporters include PIN1. |
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Term
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Definition
Auxin uptake
When auxin moves into the cell from the middle lamella. The carrier is a H+ co-transporter, active or passive movement. |
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Term
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Definition
| Root cortical cells redirect auxin into the rootward transport system at the boundary of the elongation zone. Allows root growth to continue for a time, independent of auxin from the shoot, and moves auxin synthesized in the root tip into the reflux stream. |
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Term
| Auxin response elements (AuxRE) |
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Definition
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Term
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Definition
Lateral meristems
A secondary meristem. Indeterminate growth. Deactivated, and are reactivated by hormones, depending on the species. Some are activated if the SAM is damaged. Some plants have many branches. |
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Term
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Definition
| Normally degraded following auxin interaction. Mutants are dominant gain-of-function mutations. The mutation prevents degradation, causing a phenotype similar to a multiple arf mutant. |
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Term
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Definition
| Ecotypes of Arabidopsis used for creating and isolating mutants. Some common ones are Columbia (Col), Landsberg erecta (Ler), Wassilewskija (Ws), and Nossen. |
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Term
| Bacterial phytochrome-like proteins (BphP) |
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Definition
| Regulate biosynthesis of photosynthetic apparatus in Rhodopsuedomonas palustris and pigments in Deinococcus radiodurans and Rhodospirillum centenum. The phytochrome in the fungus Aspergillus nidulans appears to play a role in sexual development. |
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Term
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Definition
| A triploid plant, which can only reproduce asexually. As such, all Cavendish banana plants are gentically identical. This is risky because it could go extinct if there is a pathogen that wipes them all out. Ripened in the store with ethylene gas. Brown, over-ripe bananas are sweet because starch is converted into sugar. |
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Term
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Definition
| One of the cells formed from the first division of the zygote. Longer, and with a less dense cytoplasm than the basal cell. Undergoes a series of transverse divisiosn to produce the suspensor. Also produces the hypophysis. |
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Term
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Definition
| Movement of auxin towards the base of a plant. In the shoot, this is downwards. In the root, this is upwards. |
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Term
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Definition
| The major plant hormones. Should be called Big 7 because there are seven. They are auxin, gibberellin, cytokinin, abscisic acid, ethylene, brassinosteroids, and stroglactones. |
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Term
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Definition
| One of the Big 5. A plant hormone. |
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Term
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Definition
| Have no strategy to reduce photorespiration. The first molecule that CO2 binds to has 3 carbons. PGA is an immediate product of CO2 fixation. Mesophyll cells fix CO2 and perform Calvin cycle reactions. Bundle sheath cells lack chloroplasts. Not well adapted to dry or hot areas where stomata benefit from being closed. |
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Term
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Definition
| Extant intermediate species in C4 evolution. Have normal photosynthesis, with Kranz anatomy. |
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Term
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Definition
| A strategy to reduce photorespiration. Altered chemistry by different anatomy; spatial separation of CO2 fixation and the Calvin cycle. The first CO2 molecule binds to an oxaloacetate molecule; some energy is spent transporting it to the bundle sheaths. Has Kranz anatomy. Bundle sheath cells perform Calvin cycle reactions. Rubisco is 10 times more effective due to 100 x increase in CO2 concentration. Stomata do not have to be open as much. Adapted to hot, dry, or salty conditions. C4 plants have evolved independently in over 40 taxa. Includes corn and sorghum. |
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Term
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Definition
| A project started in the early 2000s to breed rice into a C4 plant. It would take thousands of years to reach this goal. |
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Term
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Definition
| A culture of undifferentiated cells. It can be made to differentiate into plant tissues by exposure to hormones. Similar to a plant tumour. |
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Term
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Definition
Carbon cycle
Carbon reactions of photosynthesis
Calvin cycle
Dark reactions
Photosynthetic carbon reduction cycle
Reductive pentose phosphate cycle
Stroma reactions
The metabolic cycle that reduces CO2 into organic compounds. The second step of photosynthesis, occurring in the stroma. Independent of light. Chemical energy produced in the light reactions is used to fix CO2, which is reduced to carbohydrates. It takes 3 ATP and 2 NADPH to fix one carbon atom. Products provide substrates for enzymes, and control its catalytic rate. Three steps: carboxylation, reduction, and regeneration. |
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Term
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Definition
Crassulacean Acid Metabolism
A strategy to reduce photorespiration. Altered chemistry by different timing of carbon fixation. CO2 is fixed at night, and stored in the vacuole as acid. Stomata are closed in the day and open at night. Plants grow very slowly. |
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Term
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Definition
| A shoot meristem which arises independently of the SAM. Found in woody plants. Increases the girth of the stem. |
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Term
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Definition
| Mature leaves perceive CO2 levels and transmit information to developing leaves. Plants in high CO2 levels produce new leaves that have fewer stomata, and mature leaves are unaffected. |
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Term
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Definition
An activity of rubisco. Fixes a CO2 molecule.
RuBP + CO2 → 2 PGA |
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Term
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Definition
| The first step of the Calvin-Benson cycle. One reaction, catalyzed by rubisco. The CO2 acceptor molecule reacts with water and a five-carbon ribulose 1,5-bisphosphate to generate two molecules of three-carbon 3-phosphoglycerate. |
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Term
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Definition
| Mutants with indeterminate petal formation. |
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Term
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Definition
| The fertile leaf of an angiosperm which bears the ovules. A pistil is composed of one or more carpels. |
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Term
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Definition
| Prevents apoplastic movement of water and solutes into the root xylem. Water must cross plasma membrane to get across the Casparian strip. Contains suberin. |
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Term
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Definition
| One or pertaining to a stem. Cauline leaves are attached to the stem distinctly above the ground, in contrast to basal leaves. |
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Term
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Definition
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Term
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Definition
| Composed of cellulose microfibrils, embedded in a polysaccharide matrix. Porous, lightweight, and strong. Holds water to keep the cell in an aqueous environment. In leaves it has evaporative loss of water. Includes the primary and secondary cell wall. |
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Term
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Definition
| A cluster of infrequently dividing stem cells at the very tip of the SAM. Analogous to the quiescent centre of the root. |
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Term
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Definition
| Provided the first clues to the mechanism of phototropism on coleoptiles in 1880. Demonstrated that light is perceived by the tip of the plant, but bending occurs in the region below the tip. |
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Term
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Definition
| Absorbs red light, not far-red light. Found in the light harvesting complex and the reaction centre complex. Acts as an antenna to focus light onto the reaction centre complex. |
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Term
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Definition
| Organelles in which photosynthesis takes place. Derived from once free-living cyanobacteria that became endosymbionts in early eukaryotes. Has thylakoids, stroma, and grana. There are two layers of bilipid membrane. It has its own bacterial-like DNA. |
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Term
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Definition
| Phototropins are involevd. In low light, they accumulate on the upper surface of the palisade mesophyll, to maximize photosynthesis. In high light, they line up perpendicular to the direction of light, on the edge of the cells. |
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Term
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Definition
| A model that applies to all tropism reponses. Auxin in a horizontally oriented coleoptile tip is transported laterally to the lower side, causing the lower side to grow faster than the upper side. |
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Term
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Definition
| A light-absorbing prosthetic group on a photoreceptor. Absorbs light and has a conformational change that causes the protein to undergo a conformational change, chanign the activity of the protein. |
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Term
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Definition
| The plant's internal clock. Set by light patterns. Phytochrome and cryptochrome are involved. Perception of day length, mediated through interaction of light-regulation pathways. |
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Term
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Definition
| Endogenously regulated spiraling growth pattern of the shoot tip. Not all cells are expanding at the same time, producing circular movement of the seedling. Can be subtle or elaborate. |
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Term
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Definition
| A a gene which has a negative feedback loop with WUS. Expressed in stem cells, possibly due to WUS-related signals from the organizing centre. Expression in the embryo arises after WUS. Produces CLV3 protein, which interacts with more widely expressed CLV1/CLV2 receptor complex, limiting WUS expression in the organizing centre. The negative feedback loop maintains a balance between the organizing centre and stem cells. In clv3 mutants, WUS takes over and the meristem enlarges dramatically; inflorescences are dense, and floral meriestems do not stop growing after the gynoecium is formed; there is a lump in the centre of the flower. This mutation is the plant equivalent of cancer. |
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Term
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Definition
Xanthium
An angiosperm. Red light inhibits flowering in adults, in a photoperiodic response. |
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Term
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Definition
| All coffee plants are genetically identical. This is risky because it could go extinct if there is a pathogen that wipes them out. |
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Term
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Definition
| Explainst he upward movement of water in a plant. Relies on surface tension. Evaporation from th eleaves creates negative pressure. Negative pressure at the top of the plant pulls water upwards. |
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Term
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Definition
| The hypocotyl of a corn seed, surrounded by an embryonic leaf. |
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Term
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Definition
| Central cells of the root cap. Removal of these cells abolishes root gravitropism. These cells may be statocytes. A volcano-shaped secondary cell wall in the centre of the outer cell surface, that forms between the plasma membrane and the primary cell wall. They desiccate and die at maturity. |
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Term
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Definition
| Initials in Arabidopsis below the quiescent centre. Gives rise to the central portion of the root cap. |
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Term
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Definition
| In corn, they have plasmodesmata only with phloem cells. In rice, they also have plasmodesmata with other cells. |
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Term
| CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1) |
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Definition
| Includes DE-ETIOLATED (DET) and FUSCA (FUS). Encodes proteins in COP1-SPA complex and CSN complex. Functions as a light-inactivable repressor of photomorphogenesis. Has light-regulated nucleocytoplasmic partitioning; nuclear enrichment in darkness, and interacts with transcription. Acts as an E3 ubiquitin ligase, targeting light harvesting proteins for degradation. Interacts with CRY1, which is responsible for cryptochrome-mediated blue light regulation of photomorphogenesis. Mutants exhibit light-growth phenotypes when grown in the dark, and leaves are yellow. |
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Term
| COP1-SUPPRESSOR OF PHYA (COP1-SPA) complex |
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Definition
| COP1 encodes proteins in this complex. |
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Term
| COP9 signalosome (CSN) complex |
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Definition
| COP1 encodes proteins in this complex. Widely conserved in multicellular organisms. Has one-to-one subunit homology withh the lid subcomplex of the 26S proteasome. It is required for degradation of target proteins in ubiquitin-dependent protoeolysis. |
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Term
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Definition
| Genes necessary for repression of photomorphogenesis in darkness. Have hypothesized roles in proteolysis and chromatin remodeling. Degrade proteins that control development in light. Light controls the location of COP/DET in the cell; an integration point for light signals. |
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Term
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Definition
| There are over 70,000 varieties of corn in North America. Day-neutral corn is planted in Canada because short-day corn would not reach maturity in the short season. Two very similar-looking varieties can differ by up to 50% of the genome. |
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Term
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Definition
| Cells of the SAM interior to the tunica. Have more variable division patterns than the tunica. |
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Term
| Cortical-endodermal initials |
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Definition
| Initials in Arabidopsis to the side of the quiescent centre. Divide anticlinally, then periclinally to form the cortical and endodermal cell layers. |
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Term
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Definition
Gossypium hirsutum
Has trichomes which aid in seed dispersal. |
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Term
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Definition
| A leaf of the embryonic plant within a seed. |
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Term
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Definition
| Mutants of this gene have more trichomes than is normal. |
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Term
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Definition
| Photoreceptors that recognize blue and UVA light. Dominant during photomorphogenesis. Arabidopsis have two cryptochrome genes: CRY1 and CRY2. Have a strong homology to each other and other DNA photolyases. Contains deazaflavin or pterin chromophores, and C-terminal extensions not found in DNA photolyases. Includes cryptochrome 1 and 2. |
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Term
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Definition
| Active in entrainment of circadian clocks under high blue and red light. Encoded by CRY1. |
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Term
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Definition
| Plays a role in flowering. Encoded by CRY2. |
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Term
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Definition
| A waxy surface on a leaf that prevents uncontrolled water loss. |
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Term
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Definition
| Have photosynthesis and produce oxygen. Incorporated into many organisms, includign plants, red algae, and some animals. |
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Term
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Definition
| One of the Big 5. Control meristem size, which can alter the pattern of leaf emergence. Establishes boundaries. Involved in cell division, morphogenesis of shoots and roots, promotion of chloroplast maturation, cell enlargement, expansion of leaves and cotyledons, and delaying senscence. Help regulate cell cycle and cell division. May be involved with the release of axillary buds from apical dominance. Transport passively through the xylem. The ratio of cytokinins to auxins promotes root or bud development in tissue culture. |
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Term
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Definition
| Have apomixis; there is no sexual reproduction. Genetically identical every generation. |
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Term
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Definition
| A protein complex that interacts with DNA binding proteins DB1 and histone H2B, suggesting a role for chromatin remodeling in regulation of gene expression during photomorphogenesis. |
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Term
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Definition
| Determines the shape of the organism. |
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Term
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Definition
| Maturation of cells into specific cell types to form tissues. |
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Term
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Definition
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Term
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Definition
| A protein in bacteria whcih catalyzes blue/UVA-dependent repair of DNA damage. Has homology to cryptochromes. |
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Term
| Donor-receiver agar block method |
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Definition
| An agar block containing radioactively-labelled auxin is placed on the end of a tissue segment, and receiver block is placed on the other end. Movement of auxin through the tissue is determined by measuring radioactivity in the receiver block. Shows the polar movement of auxin; tissues differ in degree of polarity. |
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Term
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Definition
| Complex changes in phsiology that allow the embryo to withstand prolonged periods of inactivity. |
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Term
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Definition
| Can kill the plant if dosage is too high. |
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Term
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Definition
| A synthetic promoter made of auxin response elements. Used to locate auxin in living tissues. It is bound to the gene for a GFP. Auxin will bind to it. Doesn't tell you where auxin was produced. |
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Term
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Definition
| Plants which grow on the surface of water. |
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Term
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Definition
| A group of plants within a species that has adapted to a particular environment. Demonstrates behavioural, structural, and/or physoilogical differences from other members of the species. Genetically different. |
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Term
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Definition
| The female gamete. One is found in an embryo sac. |
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Term
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Definition
| A zone of rapid cell elongation in the root tip. Rate of division is less and less, the further from the root tip. |
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Term
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Definition
| The young plant in a seed; the young sporophyte, before it has begun to take on its mature form and size. |
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Term
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Definition
| The female gametophye. Housed in the ovule. Consists of eight nuclei, including the egg cell. |
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Term
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Definition
| The process by which a single cell is transformed into a multicellular entity having a characteristic organization. In most plants it occurs in the ovule. It has a highly predictable sequence. Polarity is established and cells organize in layers. Includes morphogenesis, organogenesis, histogenesis, dormancy, and germination. In Arabidopsis it has five stages: zygotic, globular, heart, torpedo, and mature. |
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Term
| End-of-day response (EOD) |
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Definition
| At the end of the day, if a plant is exposed to a flash of far-red light, there is stem elongation. |
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Term
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Definition
| Part of the root. Has a waxy layer that regulates water and nutrient intake. Without the endodermis, the root dies; the vasculature fills with a callose plug. |
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Term
| Engelmann's action spectrum experiment |
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Definition
| Used Spirogyra algae with a spiral chloroplast, and Aerotactic bacteria that move toward light. Separated light on the Spirogyra, and the Aerotactic bacteria moved towards where the most oxygen was produced, showing the action spectrum of photosynthesis. |
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Term
| Epidermal-lateral root cap initials |
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Definition
| Initials in Arabidopsis below and to the side of the quiescent centre. Divide anticlinally, then periclinally to form two files of cells that form the lateral root cap and epidermis. |
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Term
| Escape from photoreversibility |
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Definition
| Red light induced events are reversible by far-red light for a limited time period, after which the response is said to have "escaped" from reversal control by light. Early steps in biochemical reactions are reversible by removing Pfr, but after a certain point, reactions proceed irreversibly. |
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Term
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Definition
| A component of MS medium. Provided as a complex mixture of salts, including chlorides, sulfates, nitrates, and phosphates. |
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Term
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Definition
| Mutants of this gene have more trichomes than is normal. |
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Term
| Ethyl methanesulfonate (EMS) |
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Definition
A method to induce mutations. Mutation rate is 0.1% - 2.0%. Must screen 10,000+ plants to find 10 - 20 mutants.
1. Expose M0 flowers to EMS
2. Plant mutagenized M1 seeds
3. Harvest M2 seeds
4. Plant segregating M2 seeds form parent
5. Screen mutants |
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Term
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Definition
| One of the Big 5. Causes fruit ripening. A gaseous hormone produced by most higher plant tissues, especailly from meristematic and nodal regions. Produced in cells and diffuses as a gas through intercellular spaces and outside tissue. Invovled in leaf and flower senscence, leaf and fruit abscission, fruit ripening, root hair development, seedling growth, and hook opening. Produced during wounding or physiological stresses such as flooding, chilling, disease, or drought. |
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Term
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Definition
| Plants are grown from seed in the dark for 8 - 10 days in air. Plants grown with ethylene demonstrate triple response morphology: shortened and thickened hypocotyl, reduced root elongation, exaggerated curvature of the hypocotyl hook. If the plant lacks this response, it is an ethylene insensitive mutant. |
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Term
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Definition
| Plants grown in the dark. Hypocotyl is elongated and spindly, and leaves remain folded in hook formation. Plastids remain as protoplasts, giving leaves a yellow colour. Growth is from cell expansion, not division, but there can be some cell number increase. The maximum height varies. After a certain height, the plant is no longer viable if it reaches the light. |
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Term
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Definition
| Having two cotyledons. Arabidopsis is eudicotyledonous. |
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Term
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Definition
| Repetitive, not innovative. There are large changes as well as fine-tuning. |
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Term
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Definition
| A plant physiologist. In 1908, hypothesized that guard cell turgour is regulated by osmotic changes resulting from starch-sugar interconversions. |
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Term
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Definition
| An embryo mutant where the middle region is missing. There is no hypocotyl. The leaves are formed out of the root. |
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Term
|
Definition
| Has a role in limiting guard mother cell division. Loss-of-function mutants have uncontrolled guard mother cell division, resulting in rows of undifferentiated guard mother cells. |
|
|
Term
| FAR-RED ELONGATED HYPOTOCYL1 (FHY1) |
|
Definition
| A protein that can act as a nuclear localization signal for phytochrome A, transporting it to the nucleus. |
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Term
|
Definition
| A CLAVATA2 gene, found in maize. |
|
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Term
| Ferredoxin-thioredoxin system |
|
Definition
| Uses ferredoxin reduced by the photosynthetic electron transport chain and two chloroplast proteins to regulate fructose 1,6-bisphosphate, sedoheptulose 1,7-bisphosphate phosphoribulokinase, and NADP-glyceraldehyde 3-phosphate dehydrogenase. Links the light signal sensed by the thylakoid membranes to the activity of the Calvin-Benson cycle. |
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Term
|
Definition
| A secondary meristem. Determinate growth. A flower is composed of a fixed number of parts. The floral meristem has a unique pattern of WUS expression, which is transiently maintained. |
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Term
|
Definition
| Phytochrome and cryptochrome are involved. Flowering is induced in long day species, and repressed in short day species, when a light signal coincides with a sensitive phase of the circadian clock. |
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Term
|
Definition
The number of photons impinging on a unit of surface area. Units are micromoles of quanta per square meter.
Total fluence = irradiance x duration of irradiation |
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Term
|
Definition
| Used in reporter constructs. Includes GFP and GUS. |
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Term
|
Definition
| Give rise to leaf primordia, axillary meristems, and floral meristems. |
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Term
|
Definition
| Controls stomatal patterning and spacing in Arabidopsis. Mutants have decreased density of stomata, and poor spacing; guard cells may be placed next to one another. |
|
|
Term
| Fructose 1,6-bisphosphatase |
|
Definition
Catalyzes the third reaction of regeneration in the Calvin-Benson cycle. Regulated by the ferredoxin-thioreduction system.
fructose 1,6-bisphosphate + H2O → fructoses 6-phosphate + Pi |
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Term
|
Definition
| The study of plants helps us conserve the environment, learn about the natural world, and better harness the ability of plants to produce food, medicine, and energy. The production of food will need to increase by 70% in the next 40 years due to raising populations. Plants will need to be more water, nutrient, and pathogen stress resistant, as well as more nutritious. |
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Term
|
Definition
| A domain on the N-terminal half of phytochrome. Has bilin-lyase activity, which binds the chromophore. |
|
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Term
|
Definition
| A variety of corn which grows to be about 1 foot tall. It is already flowering as an embryo. |
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Term
|
Definition
| Named for their mutant phenotypes, rather than by gene family, because of how genetics was studied before genome sequencing. For example, shoot gravitropism genes 1 - 5 are in different families, but produce the same phenotype. |
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|
Term
| Gene vs Environment (GVE) |
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Definition
| Complex signals that cause a program to run. |
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Term
|
Definition
| The alleles which an organism has. Interact with each other and the environment to produce phenotype. |
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Term
| George Lorimer and colleagues |
|
Definition
| Discovered that rubisco must be activated before acting as a catalyst. CO2 transforms the enzyme into an active form. |
|
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Term
|
Definition
| Resumption of growth of the embryo after dormancy. Triggered by environmental cues. Begins with imbibition of water, and is completed with emergence of a radicle. A complex process involving many endogenous factors, including overcoming abscisic acid regulated dormancy through synthesis of gibberellic acid. Phytochrome is involved. Small seeds generally require light for germination. |
|
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Term
|
Definition
| One of the Big 5. A large class of chemically related compounds considered a type of plant hormones. Can regulate several aspects of plant growth and development including internode elongation, seed germination, transition into mature adult stage, floral initiation, sex determination, and fruit set. |
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Term
|
Definition
| Plays a role in trichome development. Mutants have fewer trichomes than normal. |
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Term
|
Definition
| Expression is activated in shoot epidermal cells to produce trichoblasts. Mobile inhibitors move into adjacent cells to inhibit GL2 expression, producing even spacing of trichomes. In root epidermal cells, it produces an atrichoblast. Mutants have no trichomes, and excessive root hairs. |
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Term
|
Definition
| The second stage of embryogenesis. The apical cell divides to form the octant. Further divisions form the protoderm. |
|
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Term
|
Definition
| Produce anti-herbivore compounds. Many medicinal products are made by trichomes, including the drug THC. |
|
|
Term
| Glyceraldehyde 3-phosphate (GPA) |
|
Definition
|
|
Term
|
Definition
| An embryo mutant where the apical and basal region is missing. There are no signals, and no differentiation. An amorophous mass fills the seed. It can grow only in tissue culture. |
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Term
|
Definition
| Transgenic rice with vitamin A. Prevents blindness. |
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Term
|
Definition
|
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Term
|
Definition
| A tropism in response to gravity. Independent of phototropism. Critical to germinating seeds so that the shoot is able to reach a light source before limited seed reserves are exhausted. Shoots have negative gravitropic response: grow upwards against gravity. Primary roots have positive gravitropic response: grow downwards towards gravity. |
|
|
Term
| Green fluorescent protein (GFP) |
|
Definition
| A fluorophore used in reporter constructs. It is bound to the gene or protein. The plant does not die in the process. |
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Term
|
Definition
| Many tissues throughout the plant. |
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Term
|
Definition
| Determines the size of the organism. |
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Term
|
Definition
| Epidermal cells found on the leaf, mostly on the abaxial surface. Maintain stomatal pores. Swell to open the pore; the cell fills with water. Shrink to close the pore. Play an important role in CO2 uptake and H2O transpiration, which must be balanced in land plants. In a well-watered plant, light is the dominant signal controlling stomatal movement; open when exposed to blue light. When exposed to blue light, protoplast in the cells swell, causing increase in turgor pressure. Blue light activates proton-pumping ATPase in the plasma membrane, causing surroundings to become more acidic. Can also open and close in response to temperature, humidity, and CO2 concentrations. In Arabidopsis, guard cells are formed through a tightly controlled series of cell divisions forming a protodermal cell, meristemoid mother cell, and guard mother cell before differentiating into guard cells. |
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Term
|
Definition
| Swell when exposed to blue light. Light stimulates uptake of ions, decreasing osmotic potential, causing influx of water. |
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Term
|
Definition
| The third cell that forms in the differentiation of guard cells. The meristemoid mother cell differentiates into it. It has symmetric division, and differentiation to produce a pair of guard cells. FAMA is necessary for this division and differentiation. |
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Term
|
Definition
| An embryo mutant where the apical region is missing. There is no apical-basal division. Only a root forms. |
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Term
|
Definition
| A fluorophore used in reporter constructs. Cheaper, and produces a crisper image, but the plant dies in the process. Expresses blue in livign tissues. Kills the plant because it produces a toxic by-product. |
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Term
|
Definition
| The third stage of embryogenesis. About 250 cells. Cell division on either side of the shoot apical meristems forms two cotyledons, establishing bilateral symmetry. The basic body plan of the embryo is formed. WUS-positive cells of the shoot meristem remain next to precursors of the vascular system. |
|
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Term
|
Definition
| A prosthetic group on a molecule that contains a metal ion. Found in hemoglobin, chlorophyll, and cryptochrome. |
|
|
Term
| High-irradiance response (HIR) |
|
Definition
| A phytochrome that requires prolonged or continuous exposure to light at relatively high irradiance (not fluence). Depends on the intensity of light. Continuous irradiation can be replaced by very frequent pulses of light. Includes synthesis of flavonoids, inhibition of hypocotyl elongation, induction of flowering, plumular hook opening, enlargement of cotyledons, and production of ethylene. |
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Term
|
Definition
| An asepct of embryogenesis. Differentiation of cells to produce anatomically and functionally diverse tissues. |
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Term
|
Definition
| In 1856, proposed that turgour changes in guard cells provided mechanical force for changes in stomatal apertures. |
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Term
|
Definition
| Mutants have elongated hypocotyls in the dark as well as in the light. Some are defective in chromophore synthesis, and some are missing the gene for phytochrome. |
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Term
|
Definition
| Elongates repidly towards the soil surface when the testa is split. It remains hooked while penetrating the soil, with the two cotyledons together to protect the SAM. |
|
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Term
|
Definition
| The only portion of the embryo which is derived from the basal cell. The top cell of the suspensor. Gives rise to essential cells in the root apical meristem, including the columella and quiescent centre. |
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Term
|
Definition
| Cells where auxin accumulates. |
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Term
|
Definition
| Mutants show defect in apical dominance. |
|
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Term
|
Definition
| Involved in embryonic development and seed set. |
|
|
Term
| Indole-3-acetic acid (IAA) |
|
Definition
| A small molecule chemically related ot tryptophan. The most common, abundant, and important form of auxin. Naturally occurring. Membrane impermeable, requiring carrier-mediated active transport. Primariy produced in the shoot meristem, young leaves, and developing seeds and fruits. Often found in growing tissues with rapidly dividing cells. Important in determining effect on growth. |
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Term
|
Definition
| The time lag between onset of illumination and increased rate of CO2 fixation. |
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Term
|
Definition
| Produces spacing patterns of trichomes and guard cells. Involved extracellular inhibitory signalling. |
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Term
|
Definition
| A cluster of cells that have a slow rate of division and undetermined fate. Descendants of initials take on different fates according to radial and longitudinal organization and development of lateral organs. |
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Term
|
Definition
| A shoot meristem which arises independly of the SAM. Found in grasses. Contribute to the lengthening of the stem. Flanked by differentiated tissues. Includes the vascular cambium. |
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Term
|
Definition
| Communication between cells. Simple cascades and movements within a tissue. |
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|
Term
| International space station |
|
Definition
| A flower recently bloomed on the space station. This is important for space travel to Mars. It is unknown if seeds can form in zero gravity. |
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Term
|
Definition
| A mutation that produces horizontal branches rahter than branches angled upwards. Related to gravitropism. |
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Term
|
Definition
Fluence rate
Units are micromoles of quanta per square meter per second. |
|
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Term
|
Definition
| Mutants have defective phototropic response. Lack light-activated photophosphorylation. Provided the first genetic link between blue light mediated phototropism and photophosphorylation. |
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Term
|
Definition
| An STM-related gene repressed by AS1. Encodes a transcription factor. |
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Term
|
Definition
| Anatomy found in C4 plants. Mesophyll cells form wreaths around bundle sheaths. Starch accumualtes in bundle sheaths, where Calvin cycle reactions are occurring. |
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Term
|
Definition
| The outermost layer of the tunica. |
|
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Term
|
Definition
| The layer of the tunica beneath L1. |
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Term
|
Definition
| The layer of the tunica beneath L2. Also gives rise to the corpus. |
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Term
|
Definition
| Most leaves have polarity and have different functions on the abaxial vs. adaxial surfaces. |
|
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Term
|
Definition
| Arise de novo from small groups of cells in internal tissue layers of the pericycle. Arise due to signs from spacing and/or water, depending on species. After receiving an auxin signal, the pericycle cells un-differentiate and begin to divide. The lateral root meristem forms after a few typical root cells are produced first. |
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Term
|
Definition
| The reciprocal relationship between fluence rate and time. VLFRs and LFRs obey the law, but not HIRs. |
|
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Term
|
Definition
Early leaves
Derive from primordium founder cells. Determinate growth. The distance from the meristem centre, and the distance from other leaf primordia limit where leaf primordia form; auxin is important for this process. They initiate where auxin accumualtes, according tot he phyllotaxy of the species. |
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Term
|
Definition
| Cells change from vascular cells into epidermal cells when leaves fall off. |
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Term
|
Definition
| Typically produced directly by the primary meristem. A leaf starts as a leaf primordium. |
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Term
|
Definition
| Hard to study. Individuals are made by crossing two heterozygotes. Dominant lethal mutations are impossible to study. |
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Term
|
Definition
Lactuca
An angiosperm. Red light pulses promotes germination of seeds, and far red light flashes undoes this. |
|
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Term
|
Definition
| The most important environmental cue that regulates plant development. Plants can sense light direction, intensity, quality, and periodicity. Controls phototropism, photomorphogenesis, chloroplasts differentiation, germination, and flowering. Influences organization of organelles, and has effects on development during all stages of plant life. Acts as a primary source of energy through photosynthesis. |
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Term
|
Definition
|
|
Term
|
Definition
The first step in photosynthesis, occurring in the thylakoid. Light energy is converted into chemical energy. Chlorophyll of the light harvesting complex focuses light onto the reaction centre. PSI and PSII act together to split a water molecule and create chemical energy in the form of NADPH and ATP. Protons are pumped into the thylakoid to produce a proton gradient that is used by ATP synthase to produce ATP.
H2O → O2 + H+ + e- |
|
|
Term
|
Definition
| Once the fate of a cell is established, it becomes committed to a fixed program of development. This system is found in many animals, but not in plants. Although in roots files of cell-types are made, differentiation is determined by signals from tissues, and not lineage-dependent. |
|
|
Term
| Low fluence responses (LFR) |
|
Definition
| Phytochrome responses initiated by fluences 1.0 μmol/m2, and are saturated at about 1000 μmol/2. Includes promotion of lettuce seed germination, inhibition of hypocotyl elongation, and regulation of leaf movements. Typified by red/far-red reversibility response. |
|
|
Term
| M. Calvin, A. Benson, J.A. Bassham, and colleagues |
|
Definition
| Provided convincing evidence for the Calvin-Benson cycle. |
|
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Term
|
Definition
| Exclude salt uptake at their Casparian strips. |
|
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Term
|
Definition
| Meristem at the edges of developing organs. |
|
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Term
|
Definition
| A zone of the root where cells differentiate. Elongation ceases. Lateral roots and root hairs may begin to form. |
|
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Term
|
Definition
| The fifth stage of embryogenesis. Storage compounds accumulate in cells, the emrbyo and seed lose water, and become metabolically inactive as they enter dormancy. |
|
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Term
|
Definition
| A group of cells that retain ability to proliferate. Maintain embryonic potential. Subject to modification by external factors, giving plants developmental plasticity. |
|
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Term
|
Definition
| A zone of the root tip under the root cap. A cluster of cells that act as initials. Divide to form cells that divide and differentiate. Cells are not elongating. |
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Term
|
Definition
| Small clusters of cells that give rise to trichomes or stomata. |
|
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Term
|
Definition
| The second cell that forms in the differentiation of guard cells. Produced by an asymmetric division of the protodermal cell. Differentiates into the guard mother cell. MUTE is necessary for this differentiation. |
|
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Term
|
Definition
| A component of MS medium. Buffers the medium, maintainign a pH around 5.7. |
|
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Term
|
Definition
| Produces small seedlings on its leaves for asexual reproduction. |
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Term
|
Definition
| A scale used when preparing digital images. A scale of 1 cm divided into 10 mm, and then into 10 units of 0.1 mm. Mounted on the microscope, and photographed with the objective lens. |
|
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Term
|
Definition
| The bottom 4 cells of the octant. Gives rise to the hypocotyl and the upper RAM. |
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Term
|
Definition
| Has a response to heat: the leaves fold up. Protects the plant from herbivores or fire. |
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Term
|
Definition
| Over-expression of a gene. Doesn't work in some tissues. |
|
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Term
|
Definition
| Produces reduced function. Replaces an amino acid with an interchangeable amino acid. |
|
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Term
|
Definition
| An embryo mutation where the basal region is missing. Lacking auxin response factor. The hypophysis fails to develop into a quiescent centre, and no root tissue develops. Only a shoot forms. |
|
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Term
|
Definition
| An aspect of embryogenesis. Elaboration of form. |
|
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Term
|
Definition
| Algae. A chlorophyte. Red light promotes orientation of chloroplasts to the direction of dim light in the mature gametophyte. |
|
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Term
|
Definition
| In a myxospermous seed, composed of two layers of pectin. The outer layer is water-soluble and can be removed by agitation. The inner layer is sticky and remains attached. May be visualized by dying with TBO. |
|
|
Term
| Murashige and Skoog (MS) medium |
|
Definition
| Used to grow plant tissue cultures. Contains essential elements, organic supplements, sugrose, agar, and MES. |
|
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Term
|
Definition
Sinapis
An angiosperm. Red light promotes formation of leaf primordia, development of primary leaves, and production of anthocyanin in seedlings. |
|
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Term
|
Definition
| Created through selective breeding or direct genetic manipulation. May be produced by irradiation, chemicals, insertion of genes, or CRISPR/Cas9 system. |
|
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Term
|
Definition
| Promotes differentiation of guard mother cells from meristemoid mother cells. In loss-of-function mutants, no guard cells form. In plants that over-express MUTE, all epidermal cells differentiate as guard cells. |
|
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Term
|
Definition
| Seeds found in the Brassicaceae family. After imbibition over 1 - 2 days, the mucilage swells, breaks the primary seed coat, and is extruded from the trough around the columella. |
|
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Term
|
Definition
| Synthetic auxin. Membrane permeable. |
|
|
Term
| NADP-glyceraldehyde-3-phosphate dehydrogenase |
|
Definition
Catalyzes the second step in reduction of the Calvin-Benson cycle. Regulated by the ferredoxin-thioreduction system.
1,3-bisphosphoglycerate + NADPH + H+ → glyceraldehyde 3-phospate + NADP+ + Pi |
|
|
Term
|
Definition
| A source of chemical energy. Transfers H+ to other reactions. |
|
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Term
|
Definition
| Growth away from light. Occurs in primary roots. Its function is unclear. Decreased growth of cells on the "shaded" side of the stem, and increased growth on the side towards the light. |
|
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Term
|
Definition
| A phototropin that fuses with phytochrome in Mougeotia algae, allowing red light to signal responses normally mediated by blue light, such as movement of chloroplasts. |
|
|
Term
| Next generation sequencing |
|
Definition
| Can be used to screen for mutants. Uses 5' and 3' flanking primers. Very fast. Costs about $800/plant (and you will want triplicate extracts). You also need to sequence the parent plant for comparison. Plants are sequence in groups to narrow down where to look. |
|
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Term
|
Definition
| Nuclear localization signal. |
|
|
Term
|
Definition
| Epidermal cells found on the root, which lack root hairs. |
|
|
Term
| Nottingham Arabidopsis Stock Centre (NASC) |
|
Definition
| Provides seed stocks of Arabidopsis. |
|
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Term
|
Definition
| Mutants have a defective phototropic response. |
|
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Term
|
Definition
| Non-photochemical quenching. Mutants lack specific blue light responses; there is a lesion in the enzyme that converts carotenoid violaxanthin into zeaxanthin. |
|
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Term
|
Definition
| Plants folding their leaves at night. |
|
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Term
|
Definition
Avena
An angiosperm. Red light promotes de-etiolation in etiolated seedlings. |
|
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Term
|
Definition
| A spherical structure with eight cells that forms from the apical cell during globular stage of embryogenesis. |
|
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Term
|
Definition
| Sensitive fern. A pteridophyte. Red light promotes growth in the young gametophyte. |
|
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Term
|
Definition
| A phyllotaxy of leaves where there are two leaves per node, alternating at 90º each node. |
|
|
Term
| Orange carotenoid protein (OCP) |
|
Definition
| A 35 kDa soluble protein assoicated with the phcobilisome antenna of PSII in cyanobacteria. Has a noncovalently bound carotenoid, 3'-hydroxyechinenone. Essential for induction of photoprotection. |
|
|
Term
|
Definition
| A component of MS medium. Vitamins and amino acids. The presence of B vitamins helps promote adequate plant growth in culture. Includes thiamine-HCl, myoinsitol, nicotinic acid, and pyridoxine-HCl. |
|
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Term
|
Definition
| An aspect of embryogenesis. Formation of functionally organized structures. |
|
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Term
|
Definition
| A four-carbon molecule that is the immediate product of CO2 fixation in C4 plants. It is transported into bundle sheaths. |
|
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Term
|
Definition
| A by-product of photosynthesis. Used for normal cellular respiration in plant cells; this is most noticeable at night. |
|
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Term
|
Definition
| A primary photosynthetic tissue in the leaf. Cells are ordered. |
|
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Term
|
Definition
| A domain on the N-terminal half of phytochrome. |
|
|
Term
|
Definition
| The domains which comprise the chromophore-binding, photosensitive region of phytochrome, on the N-terminal half. |
|
|
Term
|
Definition
| A domain on the C-terminal half of phytochrome. Mediates phytochrome dimerization. |
|
|
Term
|
Definition
| Epidermal cells found on the leaf. The basic structure of the leaf epidermis. Form an impermeable layer. |
|
|
Term
|
Definition
Pisum
An angiosperm. Red light inhibits internode elongation in adults. |
|
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Term
|
Definition
| A polysaccharide complex. |
|
|
Term
|
Definition
| Cell walls form parallel to the tissue surface. Contributes to establishment of new cell layers. Creates new cell files. |
|
|
Term
|
Definition
| Part of the root. Lateral roots arise from the pericycle from differentiated cells. In some plants it is a storage organ and cannot form lateral roots. |
|
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Term
|
Definition
| A lateral zone of the SAM. Cells with dense cytoplasm that divide more frequenctly. Produce cells that become lateral organs such as leaves. |
|
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Term
|
Definition
| A member of the inner set of floral leaves, usually coloured or white and serving to attract pollinators. |
|
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Term
|
Definition
| The far red light-absorbing form of phytochrome. Pale cyan-green colour. The active form. Absorbs far red light, 730 nm. Far red light rapidly converts it into Pr. Darkness slowly converts it into Pr. Allowed into the nucleus. |
|
|
Term
|
Definition
| The observable characteristic of a plant that results from its genotype in relation to its environment. |
|
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Term
|
Definition
| Moves fixed carbon from source to sink. Transport can be bidirectional. Cells are connected symplastically. Companion cells keep elements alive. |
|
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Term
|
Definition
| A three-carbon molecule produced in photorespiration. Useless to the plant; it can only be reverted back into PGA. |
|
|
Term
|
Definition
Ribulose 5-phosphate kinase
Catalyzes the tenth reaction of regeneration in the Calvin-Benson cycle. Regulated by the ferredoxin-thioreduction system.
ribulose 5-phosphate + ATP → ribulose 1,5-bisphosphate + ADP + Pi |
|
|
Term
|
Definition
| Producing food from sunlight. The endosperms and cotyledons provide nourishments to the seedling until it becomes photoautotrophic. |
|
|
Term
|
Definition
"Light"
De-etiolation
A rapid developmental growth process that occurs when light is perceived at the soil surface. Hypocotyl elongation slows, the hook straightens, cotyledons separate and expand, the SAM produces new leaves. Initiates production of chlorophyll, causing greening of organs including the stem, cotyledons, and leaves. Upward growth against gravity. Allows buried seeds to emerge through the soil, reach light, and switch to a developmental pattern optimal for photosynthesis. Results from coaction of phytochrome absorbing red light and cryptochrome absorbing blue light. Auxin, cytokinins, brassinosteroids, abscisic acid, and ethylene are involved. PhyA controls seedlings in the dark, and when light is reached it is degraded, and phyB and cryptochromes become dominant. |
|
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Term
|
Definition
| Plants unfloding their leaves at dawn. |
|
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Term
|
Definition
| Plants flowering at specific times of the year in response to changing day length. |
|
|
Term
|
Definition
| Seeds requiring sunlight to germinate. |
|
|
Term
|
Definition
| Receptor molecules that plant use to detect sunlight. Respond to signals and initiate signalling reactions that typically involve second messengers and phosphorylation cascades. Absorb a photon of a certain wavelength and use the energy to initiate a photoresponse. Most consist of a protein with a chromophore synthetic group. Lower case is used when the chromophore is present, and uppercase when it is absent. Includes phytochromes, cryptochromes, phototropins, ZEITLUPE and UV RESISTANCE LOCUS 8. |
|
|
Term
|
Definition
Oxygenase activity
An activity of rubisco. An O2 molecule is "fixed". Energy is wasted converting phosphoglycolate into PGA. 50% of energy produced by a C3 plant is wasted on photorespiration; can decrease fitness in hot, dry areas.
RuBP + O2 → PGA + phosphoglycolate |
|
|
Term
|
Definition
Photochromism
The conversion-reconversion property of phytochrome; it can be conevrted back and forth between Pr and Pfr forms. Measured in vivo and in vitro with almost identical results. Conversion is associated with a conformational change in the dimer that is still unresolved.
Pr ↔ Pfr |
|
|
Term
|
Definition
| The equilibrium of 98% Pr and 2% Pfr, which is achieved by exposing phytochrome to broad-spectrum far red light. |
|
|
Term
|
Definition
Two steps, taking place in different areas of the chloroplast: light reactions, and carbon cycle.
6 CO2 + 6 H2O → C6H12O6 + 6 O2 |
|
|
Term
|
Definition
| Acts with PSII to split water and create chemical energy in the form of NADPH and ATP. |
|
|
Term
|
Definition
| Acts with PSI to split water and create chemical energy in the form of NADPH and ATP. |
|
|
Term
|
Definition
| A photoreceptor that mediates the effects of UVA/blue light. The most recently characterised photoreceptor. Regulates phototropism, chloroplast movements, adn stomatal opening. Includes neochrome, and phototropin 1 and 2. |
|
|
Term
|
Definition
| A 996 residue protein with two LOV domains at the N-terminus for light, oxygen, and voltage-regulated proteins, and a serine/threonine kinase domain at the C-terminus. Noncovalently binds flavin mononucleotide (FMN) through its LOV domains. Can undergo blue light dependent autophosphorylation. Mediates phototropism under all intensities of light. Has a minor role in chloroplast relocation. |
|
|
Term
|
Definition
| Has two LOV domains, binds to FMN, and exhibits photochemical activity similar to Phot1. Mediates phototropism under high intensity blue light. The major photoreceptor for chloroplast relocation. |
|
|
Term
|
Definition
| Tropism in response to light. One of the first aspects of light-regulated plant development to be studied. Phototropins are involved; responds only to blue light. Gradient of responsiveness to auxin produces the differential rates of growth seen on either sides of the growing organ; cell elongation on the shaded side of the shoot. |
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Term
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Definition
| A domain on the N-terminal half of the phytochrome. Stabilizes the phytochrome in the Pfr form. |
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Term
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Definition
"Leaf order"
The pattern of leaf initiation on the meristem. Determined by the pattern of primordia formation. Determines the shape of the plant. Flowers also have phyllotaxy. Includes alternate, opposite, whorled, and spiral. Can be observed using horizontally oriented large plates. |
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Term
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Definition
"Plant colour"
The most studied plant photoreceptor. Absorbs red and far red light most strongly, and some amount of blue light. Mediates many aspects of vegetative and reproductive development. Can promote photomorphogenesis. Has a molecular mass of 125 kDa, and in its functionally active dimeric form it is 250 kDa. Has a tetrapyrrole chromophore. A "hinge" region separates the N-terminal and C-terminal portions of the molecule. The N-terminal half has PAS-GAF-PHY domains. In the nucleus, phytochromes directly interact with transcriptional regulators to change gene regulation for long term changes. In the cytosol it regulates membrane potentials and ion fluxes for rapid changes. Many have evolved from a bilin-sensor protein in bacterial progenitors of chloroplasts. Has photoreversibility: there are two photoreverisble forms: Pr and Pfr. There are five phytochromes in Arabidopsis: phy A - E. There are two types: Type I and II. There are three modes of action: VLFR, LFR, and HIR. |
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Term
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Definition
| A type I phytochrome. Mediates responses to continuous far red light. It is rapidly degraded as Pfr, and controls plant responses to VLFRs, and far red HIR. Plays a role in germination, skotomorphogenesis, and flowering. Mutants that lack phyA are tall and spindly, and do not germinate in response to flashes of light. |
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Term
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Definition
| A type II phytochrome. Mediates HIRs to continuous red or white light. Regulates LFRs such as photoreversible seed germination. Regulates red/far-red reversible germination. Plays roles in photomorphogenesis and shade avoidance. Active in entrainment of circadian clocks under high blue and red light. Mutants that lack phyB are deficient in chlorophyll and some mRNAs that encode chloroplast proteins, have impaired ability to respond to plant hormones, and are unable to resopnd to low-fluence red light. |
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Term
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Definition
| A type II phytochrome. Has a role in shade avoidance. |
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Term
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Definition
| A type II phytochrome. Has roles in germination and shade avoidance. |
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Term
| Phytochrome interacting factors (PIF) |
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Definition
| A family of transcription factor proteins that act primarily as negative regulators of photomorphogenic responses. Activate "morning genes" such as light harvesting complexes and rubisco. Represses "evening genes" such as circadian clock. Regulates various aspects of phytochrome-mediated photomorphogenesis including seed germination, chlorophyll biosynthesis, shade avoidance, and hypocotyl elongation. Transcriptional activators of dark-induced genes. Promote skotomorphogenesis. Pfr degrades PIFs by phosphorylation and degradation by proteasome complexes; this provides a mechanism for modulating light responses. |
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Term
| Phytochrome kinase substrate (PKS) |
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Definition
| Membrane-associated proteins that modify phytochrome activity via phosphorylatoin, either directly, or with interactions with other kinases. |
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Term
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Definition
| The chromophore of phytochrome in higher plants. A linear tetrapyrrole. Synthesized in plastids, derived from heme via a pathway that branches from the chlorophyll biosynthetic pathway. It is exported from the plastid, and forms a thioester linkage to a cysteine residue on the PHY apoprotein. |
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Term
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Definition
| Located in the nucleus. Some interact with Pfr. |
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Term
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Definition
| A basic helix-loop-helix transcription factor. Localized in the nucleus. Interacts with phyA and phyB. |
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Term
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Definition
| A gene which creates directional movement of auxin in the plant. Encodes an auxin transport protein that pumps auxin into I1 cells. Mutants for pin1 form very few lateral organs; the stem is tall and leafless. These mutants can be made to form primordium outgrowths by applying a drop of endogenous auxin near the SAM. |
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Term
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Definition
Pinus
A gymnosperm. If you remove the SAM, the tree will not grow straight, making it undesirable for use as a ship's mast. Weevils may eat the SAM, causing this problem. Red light enhances the rate of chlorophyll accumulation in seedlings. |
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Term
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Definition
| Encodes an Arabidopsis aquaporin. Mutants have more root growth because water movement is slowed down, and the plant experiences water stress. |
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Term
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Definition
| A molecule required for survival of stem cells in flies. It is realted to ZWILLE/PINHEAD. |
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Term
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Definition
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Term
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Definition
| Signaling molecules. Chemical messengers or signalling molecules that mediate intercellular communication in different organs, in part by interacting with specific cellular protein receptors. Mediate tropic movement. Includes the Big 5. |
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Term
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Definition
| Produce most of the oxygen we breathe, food we eat, fuel we burn, and products we use. Plants produce a huge amount of useful chemicals. Plants respond to the environment developmentally. They are autotrophic, immobile, and have elaborate life cycles. They may reproduce sexually and/or asexually. Plants do not establish a germ line. Most plant development happens post-embryonically. The best existing mechanism for turning sunlight into chemical energy. |
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Term
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Definition
| A cytoplasmic connection between two cells that form in pits. Regulated and controlled passage. Structure proteins maintain its shape and size. The ER may be continuous within the plasmodesmata. |
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Term
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Definition
"Several"
Stem cells which can give rise to a restricted spectrum of cell types. |
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Term
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Definition
| Long day plants, which won't flower in Canada. A light is flashed mid-way through the night to trick the plant into flowering. Must occur at a very specific time in the night. |
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Term
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Definition
| Common to the embryogenesis of all plants. Embryos become polarized along the apical-basal axis and radial axis. |
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Term
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Definition
| The male gametophyte. Consists of a vegetative cell, encompassing two sperm cells. |
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Term
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Definition
Moss
A bryophyte. Red light promotes replication of plastids in germings. |
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Term
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Definition
| Growth towards light. Occurs in stems. An adaptation to maximize photosynthesis during early development and following the formation of gaps in a dense canopy. Increased growth of cells on the "shaded" side of the stem, and decreased growth on the side towards the light. |
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Term
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Definition
| The red light-absorbing form of phytochrome. Cyan-blue colour. The inactive form, but has some biological activity. Absorbs red light, 660 nm with an absorption maxima at 666 nm. Red light converts it into Pfr. Present in dark-growth, etiolated seedlings. Excluded from the nucleus. |
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Term
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Definition
| The outer layer of the cell wall, found in all plant cells. |
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Term
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Definition
| Meristems present in a plant seedling. Includes the SAM and the RAM. Produce 99% of the adult plant. Formed early in embryonic development. |
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Term
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Definition
| Rapidly up-regulate following a shift from darkness to light. Produce early gene products that are transcription factors, activating expresion of otehr genes. Expression depends on signal transduction pathways, indepedent of protein synthesis. |
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Term
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Definition
| Groups of about a dozen cells which come from the epidermal and sub-epidermal layers of the meristem periphery. Develop into leaf primordia. |
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Term
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Definition
16 cell stage
Signals establish the fate of the hypophysis. WUS is switched on in four inner cells. |
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Term
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Definition
| An outer layer of cells which becomes the epidermis. Forms during globular stage of embryogenesis. |
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Term
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Definition
| The first cell in the differentiation of guard cells. Has asymmetric division to form the meristemoid mother cell. SPEECHLESS is necessary for this division. |
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Term
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Definition
|
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Term
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Definition
| Distribution in the spectrum. Light in the shade has different quality than in direct sunlight. |
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Term
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Definition
| A region of infrequent cell division in a meristem where files of cells in the root converge. Establishment of the QC is mediated by auxin. In Arabidopsis, the QC is four cells. The QC is adjacent to initials. It produces auxin signals which maintain the ability to divide in initials. Has the same structure and function as the organizing centre. Preserves the original stem cells as security in case some of the DNA is lost in a division. Makes the plant less prone to mutations. |
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Term
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Definition
| The axis which runs perpendicular to the apical-basal axis. Extends from the centre of the plant outwards. |
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Term
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Definition
| Contains protein and chlorophyll. Includs PSI and PSII. |
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Term
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Definition
Determines plant responses. Affects germination. Daylight = 1.2
Sunset = 0.96
Under 5 mm of soil = 0.88
Under a leaf canopy = 0.13
Ideal ratio = 1.0
Ratio in growth chambers = 12.0 (increases efficiency of plant processes) |
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Term
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Definition
| The second step of the Calvin-Benson cycle. Two reactiosn caalyzed by 3-phosphoglycerate kinase and NADP-glyceraldehyde 3-phosphoate dehydrogenase. 3-phosphoglycerate is converted into triose phosphates, by reactions driven by ATP and NADPH. |
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Term
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Definition
| Overlapping domains of function, or duplicate genes, or partial complementation. |
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Term
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Definition
| The third step of the Calvin-Benson cycle. Through a series of ten enzyme-catalyzed reactions, 3-phosphoglycerate is converted into 1,5-bisphosphate. The plant regulates its molecules perfectly, performing quantum math at nearly 100% accuracy. Enzymes are triose phosphate isomerase, aldolase, fructose 1,6-bisphosphate, transketolase, sedoheptulose, 1,7-bisphosphatase, ribulose 5-phosphate epimerase, ribulose 5-phosphate isomerase, and phosphoribulokinase. Driven by ATP. |
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Term
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Definition
| Show when and where genes are expressed or where proteins are localized during development. Fluorophores are bound to a gene or protein. Includes transcriptional fusion and translational fusion, or a combination of both. |
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Term
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Definition
| The plant begins reproductive development after a series of environmental or internal cues. Flowers form. |
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Term
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Definition
| Triggered by internal receptors and signal processing, caused by a stimulus. |
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Term
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Definition
| Proteins which are phosphorylated by sensor proteins. |
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Term
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Definition
| Making a mutation, then screening for mutant phenotypes. |
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Term
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Definition
| A zone of the SAM behind the central zone. Gives rise to internal tissues of the stem. Contain only corpus cells. |
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Term
| Ribulose 1,5-bisphosphate (RuBP) |
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Definition
| A five-carbon molecule with which CO2 reacts in carboxylation of the Calvin-Benson cycle. |
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Term
| Ribulose 5-phosphate epimerase |
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Definition
Catalyzes the eighth reaction of regeneration in the Calvin-Benson cycle
xylulose 5-phosphate → ribose 5-phosphate |
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Term
| Ribulose 5-phosphate isomerase |
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Definition
Catalyzes the ninth reaction of regeneration in the Calvin-Benson cycle
ribose 5-phosphate → ribulose 5-phosphate |
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Term
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Definition
| When grown in a drained field, it forms a solid-core root. When growth in a flooded field, it forms a hollow root for aeration. |
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Term
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Definition
| Knocks down a gene rather than knocking it out. There is a range of intensity of the knockdown. Can analyze dose-dependency. Relies on having a target: not random. |
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Term
| Root apical meristem (RAM) |
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Definition
| Found at the tip of the root. Gives rise only to main root tissues. There are two tiers of stem cells above and below the quiescent centre. The upper tier produces most root tissues. The lower tier produces the root cap. There is radial symmetry of cells, unless there is a change in the direction of root growth. |
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Term
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Definition
| The most distal region of the root. Cells are displaced away from the meristematic zone. Covers the meristem, protecting it as it moves through the soil. Perceives gravity in gravitropism, and secretes compounds that help the root penetrate the soil and mobilize nutrients. It must be worn down to signal to the root that it is growing through substrate. It is constantly replaced as older cells wear off. |
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Term
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Definition
| Epidermal cells found on the root that have root hairs. Similar to trichomes. An extension of the cell. |
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Term
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Definition
| Downward movement of auxin. |
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Term
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Definition
| A cluster of leaves or other organs arranged in a circle or disk, often basal in position. |
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Term
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Definition
Ribulose 1,5-bisphosphate carboxylase/oxygenase
The most abundant protein on Earth. 60% - 70% of soluble protein in a plant is rubisco. Catalyzes the carboxylation reaction of the Calvin-Benson cycle with no input energy. Has a slow turnover rate, 1 - 12 CO2 fixed/s. Fixes 200 billion tons of CO2/year worldwide. Two activities: carboxylase and photorespiration. Has a high affinity for CO2, and allows affinity to O2, causing photorespiration. Evolved when CO2 levels were much higher in the atmosphere. The higher the CO2 levels, the more efficient plants are
ribulose 1,5-phosphate + CO2 + H2O → 2 3-phosphoglycerate |
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Term
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Definition
| A scale used when preparing digital images. Included beside specimens photographed with a digital hand-held camera. |
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Term
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Definition
| Creates drought conditions for plants by suckign water out of roots. |
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Term
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Definition
| Controls the division that produce endodermis and cortex files in the root. Encodes a putative transcription factor. Mutants have shortened roots, with no cortex and endodermis cell files; both stay as stem cells. Hypocotyl and inflorescences lack gravitropsim, but the root has normal gravitropism. Without an endodermis, the root is killed. |
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Term
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Definition
| The inner layer of the cell wall, found in some plant cells. Can have many different compositions, depending on cell type. |
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Term
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Definition
| Require the synthesis of proteins to be expressed. |
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Term
| Secondary shoot meristems |
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Definition
| Have essentially identical structure as the primary meristem. Includes axillary and floral meristems. Arise from the SAM. Expression of WUS and CLV3 arises de novo. This process is analogous to initiation of primary meristems during embryogenesis. |
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Term
| Sedoheptulose 1,7-bisphosphatase |
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Definition
Catalyzes the sixth reaction of regeneration in the Calvin-Benson cycle. Regulated by the ferredoxin-thioreduction system.
sedoheptulose 1,7-bisphosphate + H2O → sedoheptulose 7-phosphate + Pi |
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Term
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Definition
| Histidine kinases that phosphorylate response regulator proteins. Bacterial phytochromes are light-dependent sensor proteins. |
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Term
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Definition
| A member of the outermost set of floral leaves, typically green or greenish and more or less leafy in texture. |
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Term
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Definition
| Plants sense shade by detecting a low R:FR ratio. Resources are directed to getting out of the canopy: stems elongate and leaf development and branching is reduced. Inhibition of germination, acceleration of flowering, truncated fruit development, and reduced seed set. Phytochrome is involved. Plants grown in close proximity to each other will compete for light. |
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Term
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Definition
| An adaptation to shade. The plants live in the shade. |
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Term
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Definition
Plural: shoot apices
The SAM and most of the recently formed leaf primordia. |
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Term
| Shoot apical meristem (SAM) |
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Definition
| Found at the tip of the shoot. Initial cells and their undifferentiated derivatives. Excludes adjacent regions of the apex that are partially differentiated. Gives rise to vegetative and reproductive structures above the substrate: leaves, stems, branches, secondary meristems, floral meristems, inflorescences, and flowers. In grasses, it remains near the base of the plant until flowering. |
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Term
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Definition
| A stem produces an unlimited number of leaves. WUS is expressed indefinately, unlike in floral meristems. |
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Term
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Definition
| A gene that prevents cells from entering a differentiation pathway. Represses AS1. Maintains undifferentiated state, and cells eventually become part of the stem. It encodes a transcription factor. In stm mutants, AS1 expression expands into the meristem, causing shut-down of the SAM. |
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Term
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Definition
| Upward movement of auxin. |
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Term
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Definition
| Controls the division that produces endodermis and cortex files in the root, and specifies the identity of the endodermis. Encodes a putative transcription factor which is found in the endodermal cells of the root. Mutants have shortened roots, and there is only cortex and no endodermis. Without an endodermis, the root is killed. The cortex cells cannot elongate, which causes the root to be shortened. |
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Term
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Definition
| A statistically measured difference. |
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Term
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Definition
| Produces no change in phenotype. |
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Term
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Definition
| An elongate capsule in which the two valves are deciduous from the persistent, frame-like replum to which the seeds are attached. The silique and silicle are the characteristic fruits of Brassicaceae. |
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Term
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Definition
"Dark"
Etiolated development in the dark. Promoted by PIFs. The radicle begins to grow downwards. The main root develops root hairs and lateral roots, assisting with anchoring the seedling and drawing in water and nutrients. There is hypocotyl elongation, and the cotyledons are closed, unexpanded, and protected by the apical hook. |
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Term
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Definition
| Plants bending their leaves towards the sun during its progression across the sky. |
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Term
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Definition
| Formation of an embryo without formation of a zygote. Induced after plant cells have been dissociated and taken into suspension culture. Early emrbyos are the best starting material, but adult tissue can also be used. Mutations which increase the size of the embryonic shoot meristem increase propensity to somatic embryogenesis. Can occur in leaves that miss-express transcription factors; this supports the idea that all plant cells can become stem cells. |
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Term
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Definition
| Made in 1945. Separates light into a large spectrum, in which plants are grown. |
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Term
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Definition
| Necessary for initiation of the guard cell developmental pathway. Mutants have no guard cells. |
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Term
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Definition
| The male gamete. Two are found in a pollen grain. |
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Term
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Definition
| A phyllotaxy. There is one leaf per node, rotating a certain amount each node. Arabidopsis have spiral phyllotaxy, with leaves forming clockwise or counter-clockwise, depending on where early founder cells formed. |
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Term
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Definition
| A primary photosynthetic tissue in the leaf. Unordered cells. |
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Term
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Definition
| The reserve polysaccharide that accumulates transiently in chloroplasts. It is used at night for plant growth. |
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Term
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Definition
| The innermost layer of cortical cells that surrounds the ring of vascular bundles of the shot. Continuous with the endodermis. Contains statoliths. Has a central role in the shoot gravitropism. |
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Term
| Starch-statolith hypothesis |
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Definition
| Columella cells are statocytes. Supported by several lines of evidence. |
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Term
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Definition
| Specialzed gravity-sensing cells which contain statoliths. Statoliths may trigger gravitropism responses when they sink through fluid and come into contact with the endoplasmic reticulum. Statocytes may be columella cells. |
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Term
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Definition
| Amyloplasts that function as gravity sensors. Rate of sedimentation is correlated with the time required to perceive gravitational stimulus. |
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Term
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Definition
| The vascular system of a root. |
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Term
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Definition
| Initials in Arabidopsis above the quiescent centre. Gives rise to the vascular system, including the pericycle. |
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Term
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Definition
| The cells from which all plant cells are derived. Maintained as unspecialized for extended periods of time. Totipotent; can renew themselves and give rise to many types of mature cells. Confined to the centres of shoot and root meristems. Divide slowly, giving rise to daughter cells that remain in the centre as stem cells, and daughter cells that are displaced to the periphery and enter a developmental pathway that leads to differentiation into specific cells. The rate of division is carefully controlled to maintain the size of the meristem, by the feedback loop between WUS and CLV3. Stem cells are defined by their position within the meristem. Very versatile; many cells can become stem cells after differentiation. |
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Term
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Definition
| Can be environmental or endogenous. Triggers internal receptors and signal processing which triggers a response. |
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Term
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Definition
Urtica dioica
Has trichomes with tiny barbs that exude toxins. Makes the leaves painful to touch. |
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Term
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Definition
| Pores controlled by guard cells. Allow H2O to escape, and lets in CO2. In a well-watered plant, light controls opening and closing; open in the light, closed in the dark. Development of stomata is affected by CO2 levels; in high CO2 concentration, there is a lower density of stomata in newly forming leaves. Development is also affected by light levels; in high light stomata are fewer and larger, and pavement cells also increase in size. |
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Term
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Definition
| Two guard cells, and the pore they produce between them. When the plant is grown in light, stomatal complexes and pavement cells are fewer and larger. Form early in development. Opening and closing is regulated by phototropins; both phototropins have redundancy. |
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Term
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Definition
| Releases dormancy of Arabidopsis seeds. The seed is exposed to a moist chilling period. Synchronizes germination time. Brief phytochrome-mediated light exposure plays a role. |
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Term
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Definition
|
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Term
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Definition
| The "cytoplasm" within the chloroplast. |
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Term
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Definition
| A complex polymer found in Casparian strips. Not much is known about it. It associates with the cell wall, and with the cell membrane. Impermeable to water. |
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Term
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Definition
| A CO2 molecule that reacts with ribulose 1,5-bisphosphate at the active site. |
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Term
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Definition
| A component of MS medium. A source of fixed carbon. The dissacharide that is exported from leaves to developing and storage organs of the plant. |
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Term
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Definition
| Used in a variety of roles, including seed germination, seedling development, root and leaf differentiation, floral transition, fruit ripening, embryogenesis, senescence, response to light, stress, and pathogens. Complex roles in signalling that involved interactsions with different plant hormones including ethylene, auxin, gibberellin, cytokinin, and abscisic acid. |
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Term
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Definition
| Carnivorous plants with trichomes that aid in capturing prey. The trichomes exude a syrup in which insects get stuck, and are digested by the plant. Live in areas with low N in the soil, and capture insects to supplement N. |
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Term
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Definition
| A property of water which contributes to the cohesion-tension theory. |
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Term
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Definition
| A filament which attaches the embryo to the vascular system of the parent plant. Derived from the basal cell. Six to eight cells long. |
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Term
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Definition
| Movement from cell to cell through plasmodesmata. |
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Term
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Definition
| A mutation in maize in the CLAVATA1 gene. |
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Term
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Definition
| Tropism in response to touch. Helps roots grow around obstacles, and helps vines and tendrils wrap around structures for support. |
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Term
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Definition
| The light reactions occur here. Forms grana stacks. |
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Term
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Definition
| A model proposed for phytochrome photoreversibility. The structure of the β-hairpin is changed to an α-helix during conversion from Pr to Pfr. This instigates other conformational changes in the protein. Further studies are needed before confirming the toggle model. |
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Term
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Definition
| Produce a lot of ethylene, to turn green tomatoes red very quickly. Synchronizes the ripening of tomatoes. |
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Term
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Definition
| Controls stomatal patterning and spacing in Arabidopsis. Mutants have an increased density of stomates, and spacing is poor; guard cells may form in clusters. |
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Term
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Definition
| The fourth stage of embryogenesis. Cell elongation and differentiation. Distinction between adaxial and abaxial tissues becomes apparent. |
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Term
|
Definition
"Entire"
Stems cells which can produce the entire spectrum of cell types of an organism. In mammals the only true totipotent cell is the zygote and its immediate descendants. Many plant cells continue to be totipotent throughout the plant's life. |
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Term
|
Definition
| Elongated xylem cells found in gymnosperms. |
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Term
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Definition
| Activate needed genes, and suppress unneeded genes. Balance meristem maintenance and organ initiation. |
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Term
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Definition
| Reporter constructs that measure where and when genes are expressed. This can be done for every gene. |
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Term
|
Definition
Catalyzes the fourth and seventh reactions of regeneration in the Calvin-Benson cycle.
4. fructose 6-phosphoate + glyceraldehyde 3-phosphate → erythrose 4-phosphate + xylulose 5-phosphate
7. sedoheptulose 7-phosphate + glyceraldehyde 3-phosphate → ribulose 5-phosphate + xylulose 5-phosphate |
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Term
|
Definition
| Reporter constructs that measure where the protein goes after translation. GFP is attached to the protein, and its intracellular movments are tracked. |
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Term
|
Definition
| The motive force for xylem transport. Generated by the air-water interface in the leaf. |
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Term
|
Definition
| An epidermal cell that has a trichome or root hair. |
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Term
|
Definition
Hair cells
Epidermal cells found on the leaf, mostly on the adaxial surface. Have hundreds of functions. Some reflext light to reduce UV and heat absorption. Some aid in seed dispersal. Some are glandular. |
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Term
|
Definition
| Includes glyceraldehyde 3-phosphate and dihydroxyacetone. |
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Term
| Triose phosphate isomerase |
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Definition
Catalyzes the first reaction in regeneration in teh Calvin-Benson cycle.
glyceraldehyde 3-phosphate → dihydroxyacetone phosphate |
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Term
|
Definition
| Growth movement of a plant towards or away from a stimulus. Caused by asymmetric growth of the plant axis. May be positive or negative. Includes phototropism, gravitropism, and thigmotropism. |
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Term
|
Definition
| Mutants have more trichomes than is normal. |
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Term
|
Definition
| An amino acid, chemically related to IAA. |
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Term
|
Definition
| Surface cells of the SAM. Have consistent patterns of anticlinal divisions. Have thre layers of cells, derived from separate initials: L1, L2, and L3. |
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Term
|
Definition
| The maximum number of molecules converted by an enzyme per catalytic site. |
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Term
|
Definition
| Light-liable. Degrades rapidly on exposure to red or white light. Includes phytochrome A. |
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Term
|
Definition
| Light-stable. Does not degrade on exposure to red or white light. Includes phytochromes B - E. |
|
|
Term
| UV RESISTANCE LOCUS 8 (UVR8) |
|
Definition
| A photoreceptor responsible for several UVB-induced photomorphogenesis responses. |
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Term
|
Definition
|
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Term
|
Definition
|
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Term
|
Definition
| The embryo breaks dormancy, mobilizes stored reserves, and has vegetative growth. Typically indeterminate. |
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Term
|
Definition
| Vasculature in the leaves which moves sugars out of the leaf, and water and nutrients into the leaf. |
|
|
Term
| Very low fluence responses (VLFRs) |
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Definition
| Phytochrome responses initiated by fluences as low as 0.0001 μmol/m2, saturated at about 0.05 μmol/m2. Non-photoreversible. The minute amount of light needed convertst less than 0.02% of total phytochrome to Pfr. Saturated at very low levels of active Pfr after light pulses or constant irradiation. Includes germination of Arabidopsis seeds, growth of cotyledons in dark-grown oats, and inhibition of growth of the mesocotyl. |
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| Thick xylem cells, better at transportation, found in angiosperms. |
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| Only a small amount is used for photosynthesis; most water is used to maintain turgor pressure. Plants balance water use with their root system, low resistance pathways to move water to leaves, the cuticle, stomata, and guard cells. |
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| A phyllotaxy of leaves. There are more than two leaves per node. |
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| The typical phenotype or genotype of the species as it occurs in nature. |
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| A molecular marker expressed in the pro-embryo. Initially switched on in four inner cells of the pro-embryo. As these cells divide, cells adjacent to precursors of the vascular system maintain WUS expression. Expression is induced and/or maintained by signals of the vascular system. The organizing centre of the shoot meristem, and the quiescent centre of teh root meristem are WUS-positive, and maintain adjacent stem cells. There is a negative-feedback loop with CLV3 to maintain the rate of division of stem cells. It encodes a transcription factor that regulates teh activity of other genes. Tells adjacent cells to be stem cells. It inhibits AG. In wus mutants, CLV3 takes over and the meristem shuts down. |
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| Expression of WOX5 in the SAM can rescue wus mutants. |
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| Cells that are dead; hollow tubes. Move water and minerals from roots to leaves. Unidirectional transport. Made of tracheids or vessel elements. |
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| A family of genes. Involved in primary IAA biosynthetic pathway. Mutants do not have a strong phenotype: there is redundant function between them. |
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"Slow motion"
A photoreceptor that mediates the effects of UVA/blue light. Controls day length perception and circadian rhythms. |
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| Regional cytological differences in organization of the SAM of seed plants. Includes the central, peripheral, and rib zone. |
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| A zone of the shoot meristem where daughter cells are displaced to the periphery of the meristem. New organs are formed, such as leavs. |
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| A molecule required for survival of stem cells in lpants. Reltaed to PIWI. |
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| The first stage of embryogenesis. Fusion of the haploid egg and sperm to form a single cell. The cell has polarized growth, and asymmetric transferse division, producing the apical cell and basal cell. |
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| The first stage of embryogenesis. Fusion of the haploid egg and sperm to form a single cell. The cell has polarized growth, and asymmetric transferse division, producing the apical cell and basal cell. |
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