Lecture11

Lecture11 - Review GA regulation of reserve mobilization during germination(levels of regulation dependence on presence of hormone and tissue

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1 Review • GA regulation of reserve mobilization during germination (levels of regulation, dependence on presence of hormone and tissue sensitivity, signaling mechanism(s)) • Ethylene regulation of triple response (regulation of ethylene levels, effects on growth) (Soon to be) recurring themes: • Given hormone affects multiple levels of regulation • Multiple receptors for given hormone • Antagonistic effects of hormones • Induction of response requires derepression ER Secretion GA de-represses expression GA ABA De-etiolation (“greening”) = light induced preparation for autotrophic growth •Leaves expand •Stem elongation inhibited •Chloroplasts develop thylakoid stacks •Genes required for photosynthesis and other light- dependent processes induced Regulators of etiolated vs. de-etiolated growth have been identified genetically Mutants may be either “blind” to light or constitutively de-etiolated D L D L D L Wild-type “blind” ( hy ) de-etiolated ( det ) •“blind” mutants have lost positive regulators of light response det mutants have lost negative regulators of light response (or positive regulators of etiolated growth) One class of de-etiolated mutants is defective in brassinosteroid synthesis or signaling BRs promote extreme elongation growth and inhibit plastid differentiation in dark Interact positively with auxin and GAs, negatively with ABA
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2 Brassinosteroid signaling •Receptor (BRI1-BAK1 complex) in PM •BR binding -> phosphorylation events that inhibit repressor kinase (BIN2) •Dephosphorylation of BIN2 target TFs (BES1 and BZR1) alters stability and gene expression BR BIN2 BRI1 BAK1 BES1 BR-induced genes BR-repressed genes BZR1 BIN2 BRI1 BAK1 BES1 BR-induced genes BR-repressed genes
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This note was uploaded on 04/07/2008 for the course MCDB 1B taught by Professor Weimbs during the Winter '08 term at UCSB.

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Lecture11 - Review GA regulation of reserve mobilization during germination(levels of regulation dependence on presence of hormone and tissue

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