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93 Cards in this Set
- Front
- Back
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Plant Development
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All the changes that an organisms goes through in its life cycle (cell to whole plant)
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Two forms of plant development
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growth (increase in size) and differentiation (specialized cells)
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External factors that determine development
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Light, temp, moisture, gravity, stress
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Internal factors that determine development
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Genetic makeup (DNA)
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Tissue Culture
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Growth of lants, plant organs or cell in sterile culture on an artificial liquid or solid (agar) medium
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Uses of Plant Tissue Cultures
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Scientific studies
Medicine Plant Breeding |
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What are the ways tissue cultures are used in plant breeding?
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micropropagation
mutant screening somatic hybridization genetic engineering |
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Somatic Hybridization
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Fusing non-crossable species's protoplasts by an electroshock
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Callus
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Clumps of undifferentiated cells in a tissue culture
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Somaclonal Variation
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Variation due to mutations in regenerated tissue cultures
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Genetic Engineering
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Piece of DNA w/ 1+ genes in introduced into a plant cell where it integrates into the plant's genome
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DNA construct and how is it inserted?
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Used to transform the cell/insert trait
Promoter, Favorite gene Promoter, Resistance gene via Agrobacterium or a particle gun |
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How much land current cultivate transgenic crops?
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2.7% of ag land
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What is the main form of transgenic crop?
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Herbicide resistant, followed by Bt
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How can biotechnology be used in research?
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Find out what genes/enzymes are involved in a certain process
-Gain of Function: overexpression -Loss of Function: remove gene -introduce a new gene to see effect |
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How does herbicide resistance in plants work?
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Inserting a version of the EPSPS enzyme that is not sensitive to glyphosate herbicide (different shape so does not bind to glyphosate)
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Chitinase
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A PR protein that, when overproduced, give funal resistance
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Genomics
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analyze expression levels of all the genes in an organism
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What are the three forms of genomics?
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Transcriptomics
Proteomics Metabolomics |
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Microarray
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1. All genes of an organism are put on a chip and analyzed
or 2. mRNA is isolated from a treated plant and nontreated plant, both mRNAs are added to a chip and scanned by a computer |
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Proteomics
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Looking for difference in gene expression @ protein level. Proteins are separated on a gel and compared
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Metabolomics
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Looking for differences in gene expression in metabolites
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How to analyze transport processes (3)
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Split-root experiment
Grafting experiment Reed radioactive substrate and monitor movement |
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Where does regulation of gene expression typically happen?
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At the transcription level
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How is short-term gene expression regulated?
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Enzyme activation by phosphorolatation.
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Signal Transduction
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events that lead to gene expression
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Cotyledons
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leaves in the seed (monocot and diocot)
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Hypocotyl
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plumele (shoot) under cotyledon
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Epicotyl
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plumele (shoot) above cotyledon
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What is in a seed?
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Seed coat, embryo, endosperm
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What is in an embryo?
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Cotyledons, plumele (shoot) and radical (root)
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How does a seed germinate?
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Seed imbibes water which activates metabolism and breaks down food stores. Mitosis and elongation causes radical to penetrate seed coat to get nutrients, shoot emerges. Meristem division and elongation do the rest.
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Tunica
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Epidermis of the SAM
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Corpus
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Rest of the SAM
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Secondary roots branch from the...
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pericycle
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Extensibility
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Regulation of cell wall rigidity via hormones and enzymes
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How do cells grow (2 steps)
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Wall extension: cell increases turgor pressure to expand the cell wall
Wall loosing: cell wall loses rigidity and expands w/ turgor |
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How do plants grow (2 steps)
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1. Cell division (meristems)
2. Cell elongation |
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What are the 5 main hormones, and two possible hormones
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Auxins
Gibberellins Cytokinins Abscisic Acic Ethylene -Brassinosteriods -Polyamines |
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What are the functions of auxin?
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Increase cell elongation
Induce root initiation and vascular differentation Tropic responses Apical dominance Increase abscission of old, but no new leaves (same w/ fruit) Promotes femaleness if flowers |
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What counteracts apical dominance?
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ABA and cytokinins
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Parthenocarpy
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Fruit formation w/out pollination. Results in sterile, seedless fruit
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2,4D
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herbicide with high auxin concentrations
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Functions of gibberellin
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Stem elongation
Seed germination (stimulate amylase) Promotes maleness of flowers |
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Functions of cytokinins
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Increase cell division
Shoot and root differentiation Delays senescence Promotes branching |
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What causes witch's broom?
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Bacteria induces cytokinin production, results in excessive branching
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What are the functions of abscisic acid?
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Stomatal closure (released during water stress)
Prevents early germination Increases leave abscission |
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What are the functions of ethylene?
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Stimulates ripening
Seed germination Epinasty Lowers apical dominance (?) Increases senescence |
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What are the functions of polyamines?
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Phospholipids
May affect membrane permeability |
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What are the functions of brassinosteroids?
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stimulates stem elongation in seedlings
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What are two fates of hormones?
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Deactivated by sugars or amino acids
Destroyed by oxidation |
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How does a stress result in a response? (non-lipid)
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Stress triggers a hormone. Hormone binds to receptor (glycoprotein) on membrane, which activates a secondary messenger (Ca). 2nd activates kinase enzyme, which phosphorolates ezymes/transcription factors. Genes are expressed and result in a response.
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What are the 3 steps in hormone responses?
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1. Signal Perception
2. Signal transduction pathway 3. Response |
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Response w/ fat-soluble hormones
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Stress activates hormone, which passes through membrane and binds to a receptor that directly influences transcription factors. NO signal transduction.
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Photoreceptor
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Pigment that absorbs light and becomes activated
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What are the 3 photoreceptor and what kind of light do they capture?
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Phytochrome (red/far-red)
Cytochrome (blue/UV-A) UV-B receptor |
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Red is _____ while far red is _____.
(stable/unstable active/inactive) |
Red: inactive, stable
far red: Active, stable |
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Etiolate
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long stems and underveloped leaves associated with not enough light
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Shade has a high/low red:far-red ratio?
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Low. Induces stem elongation to find light
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What are phytochromes responsible for?
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Day/night length
Can influence membrane potential May increase ATPase, which would result in kinase/gene expression |
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What are cytochromes responsible for?
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Phototropism
stomatal opening flowering flavonoid synthesis |
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What are UV-B responsible for?
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flavonoid synthesis
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Nutations
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slow helical movement of plant shoots (vines)
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Tropisms
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movement as a reaction to a stimulus (light, gravity, etc.)
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Nastic Response
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movement that is circiadia rhythm or in response to something like touch
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What are the 2 mechanisms of nastic responses?
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Differential growth (permanent)
Turgor effects (reversible) |
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How does a plant respond to gravitropism?
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Amyloplasts and statoliths fall towards gravity which puts pressure the the ER. Ca accumulates near ER and attracts auxin, which either stimulates (shoot) or inhibits (root) growth
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Shoots have a ______ while roots have a ______ response to gravitropism.
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Shoots: negative
Roots: positive |
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Thermonasty
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Temp changes that result in diurnal opening and closing of flower petal
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Nyctinasty
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Diurnal changes in leave position (Pr/Pfr increase turgor at pulvinus which causes the leaf to rise)
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Seismonasty
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Response to touch via turgor effect
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Photoperiodism
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Organism's ability to measure daylength
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Obligate vs Facultative flowering
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Obligate: plant will not flower w/out proper conditions
Facultative: plant will eventually flower |
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Vernalization
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Cold period needed for most plants to flower
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Entrainment
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synchronized endogenous rhythm to an external environmental stimulus (think TRAINed)
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Why do tulips open and close?
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Form of thermonasty. Cells on inside of petals warm up and grow faster, reverse happens at night.
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Pre-chilling/Stratification
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cold period during dry stage needed for most seeds to germinate
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3 Ways plants deal with stress
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1. Stress escapers (not present-bulbs, tubers, etc)
2. Stress avoiders (grow longer roots, etc.) 3. Stress-tolerant |
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Hardening
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Process of acclimation due to exposure to stress. Prepares the plant for more stress later
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Types of abiotic stress
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Water stress, temperature stress, salt stress, chemical stress
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Hydropassive vs. hydroactive stomatal closure
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Hydropassive: water evaporates from guard cell, causes it to close
Hydroactive: ABA binds to guard cell, limits K+, causes higher [K] outside and diffusion |
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Osmolytes
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Compounds used to decrease water potential in the roots
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Desiccation
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Drying
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Responses to cold stress
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Make membranes less saturated (less ice crystals)
Decrease osmotic potential Go into a rest state |
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Nucleatins
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prevents ice crystals form forming in the cell wall
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Affects of high temp
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denatures proteins
membranes become too fluid photorespiration desiccation |
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Responses to high temp
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hairs
decrease leave size (smaller, vertical, roll them up) increase membrane saturation Heat shock proteins |
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Ways plants deal with salt stress
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Salt regulators (excretes salts)
Salt accumulators (keeps them to lower water potential) |
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Chelator
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binds to metals. Organic acids and peptides
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Free Radical-Scavenging enzymes
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Vit C
Glutathione |
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Biotic stress responses
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1. Hypersensitive reaction
2. Pathogenesis-related proteins 3. Systemic acquired resistance |
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Hypersensitive reaction
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blocks pathogen from spreading futher by changing cell walls or killing cells around infected site
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Elicitors
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things on pathogen that signal Hypersensitive reaction
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