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45 Cards in this Set

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What does GA stimulate in plants
stem growth in dwarf & rosette plants; cell division and cell wall extensibiolity in internode
- cold temperature required for germination of certain seeds
GA (exongenous) can replace this process in some seeds
cold temperature required for flowering (vernalization)
GA (exongenous) can replace this process in some seeds
winter wheat is biennial and needs cold temps to flower. what can be done to overcome this process?
GA exogenous
What does GA regulate
regulates transition from juvenile to adult phases
woody species have different leaves, GA (exogenous) can induce Ivy to revert from mature to juvenile forms.
Describe sex determination in GA plants
moneocious plants (corn)
dicots (spinach)
What does Ga need in order to cause male flowers
short days and cooler nights to induce tassesl; spinach is opposite, staminate flower is produeced when GA is added.
How does GA effect fruit?
Promote Fruit Set – Parthenocarpic Fruit
Grapes Thompson’s seedless grapes – two treatmets – 1st to induce fruit
formation and 2nd to increase size
Mechanism of Gibberellin Action
Mobilizing Endosperm Reserves
How does GA affect seed germination. what does it activate?
Describe the various processes of where GA is formed, what is induced, where it is moved, etc.
GA formed in embryo of cereal grains; induces alpha production occurs in
aleurone layers; moves to endosperm where it breaks down starch into sugar
which is mobilized out stimulating growth (germination)
GA stimulates transcription of alpha amylase mRNA
Cytokinin: synthetic forms?
Natural forms?
synthetic: kinetin
natural: zeatin
Where is cytokinin synthesized?
in root apical meristems, small amounts in young leaves & shoot meristems
How is cytokinin transported?
through xylem tissue
What is cytokinins main function?
stimulates cell division in meristematic regions and cambiums
What inducts tubors in cytokinin?
abrobacterium tubefaciens
What is crown Gall disease?
when agrobacterium tumefaciens invades a wound it can cause the neoplstic (tumor-forming) disease called crown gall. Agrobacterium changes cell character and they divide non-stop bc of wound response. They produce an unorganized mass of tumorelike tissue called gall. Heating this tissue to 42 degrees kills bacterium. Tissues will continue to grow forming a callus.
Low kinetin/ high auxin favors?
root differentiation
higher kinetin/ lower auxin favors?
shoot differentiation
cytokinetin regulated processes
Modify Apical Dominance and Promote Lateral Bud Growth
Cytokinins Delay Leaf Senescence
Cytokinins Promote Nutrient Mobilization 21.15
Cytokinins Promote Chloroplasts Maturation 21.16
Immunological methods in kinetin
Immunological methods are very useful for cytokinin identification and quantification. Researchers can produce antibodies against cytokinins by injecting rabbits or mice with cytokinin ribosides conjugated to a protein. Monoclonal antibodies also have been generated that are highly specific for individual cytokinins. These antibodies can be used to quantitate the amount of a cytokinin in a sample by means of a radioimmunoassay (Weiler 1980). For cytokinin isolation, plant extracts are first fractionated, usually by high-performance liquid chromatography (HPLC), and the cytokinins in the fractions are detected and measured by means of a cytokinin radioimmunoassay, similar to the auxin radioimmunoassay described in textbook Chapter 19.
The cytokinin antibodies can also be used to isolate the hormone from extracts by immunoaffinity chromatography (Akiyoshi et al. 1983). Immunological methods hold great promise for the identification and quantification of naturally occurring cytokinins because the antibodies are highly specific and more sensitive than most bioassays (Morris et al. 1991, Nicander et al. 1993). Furthermore, these immunological methods are very rapid.
Absorption/action spectrum in phytochrome indicates that
red and far-red light is responsible
Seeds germinated in the dark produce pale, spindly seedlings _______.

Name the pigment responsible.
pigment is : phytochrome, a protein blue pigment common in etiolated parts of plant.
Expose a dim light to seedlings and chloroplasts will form ______.
describe the molecular structure of ethylene
when is ethylene produced
throughout the life cycle of the plant
Where is ethylene located?
abundant in young leaves and senescing organs, ripening bananas
ethylene synthesis starts with which amino acid? Name that cycle
1. methionine
2. yang cycle
etheylene is induced by ?
stress and age, auxin & cytokinin,
what inhibits ethylene?
Ag and CO2
What does ethelene do to fruit?
ripens fruit
causes senescence (fruit death)
breakdown of cells releasing organic acids
Name two classification of ethylene fruits
1. climacteric - banana, apples (ripen quickly)
2. nonclimacteric - grape, cherry (dont ripen as quickly)
Ethylene effects leafs?
leaf epinasty - tomatoes
What does ethylene stimulate?
flower senescence, root hair formation, breaks seed dormancy, induces flower formation in pineapple
what does ethylene enhance
leaf abscission
Yang cycle means
ACC, may be conjugated
Triggers abscission, stimulates ethylene production, inhibits growth and stomatal opening under envir.stress. Secondary metabolite in fungi.
A plant growth substance (phytohormone) involved in protion of stem elongation, mobilization of food reserves in seeds & ect processes. Its absence results in dwarfism of some plants. Family of diterpene acids made by terpenoid pathway in plastids and modified in ER & cytosol before reaching activated form.
Biosynthesis occurs in plastids from
carotenoid intermediates
What inactivates ABA?
Inactivated by oxidation or conjugation.
How is ABA translocated?
thrue xylem & phloem
What are the physiological effects of ABA?
Maintains seed and bud dormancy, functions during
water stress (maintain desiccation tolerance).
Seed Dormancy controlled by ABA and GA.
Immature embryos removed
from seeds develop right
Accumulates in dormant seeds and buds
1. Prevents stomatal opening by inhibiting inward
K ion channels and plasma membrane proton pumps
2. Promotes stomatal closing by activating outward
anion channels, thus leading to activation of potassium ionse
efflux channels.
Ways in which ABA prevents stomatal closing
How does ABA prevent stomatal closing
Daytime, guard cells close to keep water from being lost. K is pumped outside which keeps water concentration up inside. Stoma is now closed.
Acid growth hypothesis"
IAA activates H* ion ATPases; causes increases extensibility of cell wall causing it to extend.
Phytochrome responses can be distinguished by the amount of light required
VLFRs – very low fluence responses are nonphotoreversible

LFRs – low fluence responses are photoreversible

HIRs – high fluence responses are propotional to irradiance