Deepak yadav

m.sc-iii

University of allahabadGuided by –PRF.S.M. prasad

M.SC--IIIAllahabad university

Deepak yadav

GUIDED BY-- PRF.S. M. PRASAD

DISCOVERY OF GIBBERELLINS

1. “BAKANAE” OR “FOOLISH SEEDLING” DISEASE OF RICE : plants grew

too talkk and toppled over.

2. JAPANESE SCIENTISTS WORKED ON THE PROBLEM AND IDENTIFIED

CAUSE: INFECTION BY FUNGUS, GIBBERELLA FUJUKUROI.

3. MID 1950s: ACTIVE SUBSTANCE CRYTALIZED AND IDENTIFIED IN

ENGLAND AND US: GIBBERELLIC ACID (GA3)

Rice leaf sheath bioassay for

gibberellin

GIBBERELLIN BIOSYNTHESIS AND METABOLISM

1. GIBBERELLINS ARE SYNTHESIZED VIA THE TERPENOID

PATHWAY.

2. BASED ON ISOPRENE UNITS:

3. BIOLOGICAL ISOPRENE UNIT = ISOPENTENYL DIPHOSPHATE

LOCATIONS OF

SOME MUTANT

GENES THAT

BLOCK GA

BIOSYNTHETIC

PATHWAY IN

PEA

GA1, THE BIOLOGICALLY ACTIVE GIBBERELLIN, IS

SYNTHESIZED FROM GA20

GA1 LEVELS CORRELATE WITH INTERNODE LENGTH

Phenotypes and

genotypes of

peas with

different

gibberellin levels

Luciferase reporter construct for GA 20-oxidase

HIGHEST IN

APICAL BUD

EFFECT OF AMO-1618 ON PETIOLE ELONGATION OF

SPINACH

EFFECT OF LONG DAYS ON GA LEVELS IN SPINACH

Long Days Short Days

Effect of Long Days (High GA levels) on Tuber

Formation in Potato

Genetically Engineered Dwarf Wheat

Plants Overexpressing GA 2-ox, which

degrades GA1

KINETICS OF

GA-INDUCED

ELNGATION OF

DEEPWATER

RICE

INTERNODE

30 min

DISTRIBUTION OF CELL DIVISION FOLLOWING GA TREATMENT OF

A ROSETTE PLANT, Samolus parviflorus

Arabidopsis GIBBERELLIN RESPONSE MUTANTS WITH

DEFECTS IN SIGNAL TRANSDUCTION

1. Gibberellin-in sensitive dwarfs

2. Gibberellin-deficient mutants in which GA deficiency

has been overcome by a second suppressor mutation,

so plant looks normal (double mutant)

3. Mutants with constitutive gibberellin response

(“slender” mutants)

GAI and RGA are related repressor proteins

Repression of GA

Response Genes

GA Response

Genes

Expressed

DIFFERENT TYPES OF MUTATIONS OF GAI AND RGA

REPRESSORS AFFECT GROWTH DIFFERENTLY

Enzyme

involved in

protein

modification -

enhances

activity of

GAI and RGA

GA acts to

block action

of both SPY

and

GAI/RGA

THE CEREAL

ALEURONE LAYER

EFFECT OF GA ON CALCIUM IN BARLEY ALEURONE

LAYER PROTOPLAST

CONTROL + GA3 GA3 + ABA (ABSCISIC ACID)

Low Cytoplasmic [Ca2+] High

SUMMARY OF STEPS IN GA SIGNAL TRANSDUCTION PATHWAY