This document summarizes research on gibberellins. It describes the discovery of gibberellins from studying a disease in rice plants that caused overly tall growth. Japanese scientists identified the causal fungus and its secretion of gibberellic acid. The document then covers gibberellin biosynthesis via the terpenoid pathway, locations of genes in the biosynthesis pathway, how gibberellin levels correlate with plant growth, and effects of gibberellins on processes like petiole elongation and tuber formation. It also discusses gibberellin response mutants in Arabidopsis and the role of repressor proteins in gibberellin signaling, as well as the effect of gibberellins on calcium levels in barley ale

1. Deepak yadav
m.sc-iii
University of allahabad
Guided by –PRF.S.M. prasad

2. GUIDED BY-- PRF.S. M. PRASAD
Deepak yadav
M.SC--III
Allahabad university

3. 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)

6. Rice leaf sheath bioassay for
gibberellin

7. GIBBERELLIN BIOSYNTHESIS AND METABOLISM
1. GIBBERELLINS ARE SYNTHESIZED VIA THE TERPENOID
PATHWAY.
2. BASED ON ISOPRENE UNITS:
3. BIOLOGICAL ISOPRENE UNIT = ISOPENTENYL DIPHOSPHATE

11. LOCATIONS OF
SOME MUTANT
GENES THAT
BLOCK GA
BIOSYNTHETIC
PATHWAY IN
PEA

12. GA1, THE BIOLOGICALLY ACTIVE GIBBERELLIN, IS
SYNTHESIZED FROM GA20

13. GA1 LEVELS CORRELATE WITH INTERNODE LENGTH

14. Phenotypes and
genotypes of
peas with
different
gibberellin levels

15. Luciferase reporter construct for GA 20-oxidase
HIGHEST IN
APICAL BUD

16. EFFECT OF AMO-1618 ON PETIOLE ELONGATION OF
SPINACH

17. EFFECT OF LONG DAYS ON GA LEVELS IN SPINACH

18. Effect of Long Days (High GA levels) on Tuber
Formation in Potato
Long Days Short Days

19. Genetically Engineered Dwarf Wheat
Plants Overexpressing GA 2-ox, which
degrades GA1

20. KINETICS OF
GA-INDUCED
ELNGATION OF
DEEPWATER
RICE
INTERNODE
30 min

21. DISTRIBUTION OF CELL DIVISION FOLLOWING GA TREATMENT OF
A ROSETTE PLANT, Samolus parviflorus

22. 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)

24. GAI and RGA are related repressor proteins
Repression of GA
Response Genes
GA Response
Genes
Expressed

25. DIFFERENT TYPES OF MUTATIONS OF GAI AND RGA
REPRESSORS AFFECT GROWTH DIFFERENTLY

26. Enzyme
involved in
protein
modification -
enhances
activity of
GAI and RGA
GA acts to
block action
of both SPY
and
GAI/RGA

27. THE CEREAL
ALEURONE LAYER

33. EFFECT OF GA ON CALCIUM IN BARLEY ALEURONE
LAYER PROTOPLAST
CONTROL + GA3 GA3 + ABA (ABSCISIC ACID)
Low Cytoplasmic [Ca2+] High

34. SUMMARY OF STEPS IN GA SIGNAL TRANSDUCTION PATHWAY