Gibberellins

What is Foolish Seedling Disease?

Rice plants grow tall/spindly and pale green

How were endogenous plant gibberellins discovered?

Dwarf mutants in maize and pea were rescued with exogenous GA3 application

What is the structure and biosynthesis of gibberellins?

Hundreds of GAs identified; 4-ringed structures numbered in order of discovery; many are intermediates in biosynthetic pathway or breakdown products; 4 biologically active GAs (GA1

What is gibberellin's role in seed germination?

Promotes seed germination

What does GA do regarding phase changes?

Promotes phase changes from juvenile to adult morphology; especially important in leaf morphology changes; transition may be accompanied by changes in leaf shape

What does GA do for stem elongation?

Promotes stem elongation in some plants (rice

What is bolting and GA's role?

GA induces bolting in rosette plants; stimulates internode elongation; seen in Brassicaceae (cabbage/mustard family) plants

What does GA do regarding flowering?

Can promote flowering in some plants

What is GA's role in pollen development?

Important for pollen development; anthers and pollen grain formation defective in gamyb mutant (GAMyb = transcription factor in GA signaling)

What is GA's role in pollen tube function?

Important for pollen tube germination and elongation; rpe1 mutant has defective enzyme critical to GA biosynthesis; defective germination and pollen tube elongation rescued by exogenous GA application

What does GA do for seed and fruit development?

Important for complete development in some seeds and fruits (e.g.

What is GA's role in sex determination?

In plants with separate male and female flowers: GA treatment increases proportion of male flowers in squash

What are the components of GA signaling?

DELLA = repressor protein; PIF3/4 = transcription factors for GA mediated growth and development; SCF complex (SCF^SLY1) is E3 ligase; GA signaling requires additional protein (GID1) to form receptor complex that recruits E3 ligase