Discovery of gibberellins
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DISCOVERY OF GIBBERELLINS. “BAKANAE” OR “FOOLISH SEEDLING” DISEASE OF RICE : plants grew too talkk and toppled over. JAPANESE SCIENTISTS WORKED ON THE PROBLEM AND IDENTIFIED CAUSE: INFECTION BY FUNGUS, GIBBERELLA FUJUKUROI.

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DISCOVERY OF GIBBERELLINS

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Discovery of gibberellins

DISCOVERY OF GIBBERELLINS

“BAKANAE” OR “FOOLISH SEEDLING” DISEASE OF RICE : plants grew too talkk and toppled over.

JAPANESE SCIENTISTS WORKED ON THE PROBLEM AND IDENTIFIED CAUSE: INFECTION BY FUNGUS, GIBBERELLA FUJUKUROI.

MID 1950s: ACTIVE SUBSTANCE CRYTALIZED AND IDENTIFIED IN ENGLAND AND US: GIBBERELLIC ACID (GA3)


Discovery of gibberellins

Rice leaf sheath bioassay for gibberellin

Increasing GA3 concentration


Gibberellin biosynthesis and metabolism

GIBBERELLIN BIOSYNTHESIS AND METABOLISM

GIBBERELLINS ARE SYNTHESIZED VIA THE TERPENOID PATHWAY.

BASED ON ISOPRENE UNITS:

BIOLOGICAL ISOPRENE UNIT = ISOPENTENYL DIPHOSPHATE


Discovery of gibberellins

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


Ga 1 the biologically active gibberellin is synthesized from ga 20

GA1, THE BIOLOGICALLY ACTIVE GIBBERELLIN, IS SYNTHESIZED FROM GA20


Ga 1 levels correlate with internode length

GA1 LEVELS CORRELATE WITH INTERNODE LENGTH


Discovery of gibberellins

Phenotypes and genotypes of peas with different gibberellin levels


Luciferase reporter construct for ga 20 oxidase

Luciferase reporter construct for GA 20-oxidase

HIGHEST IN APICAL BUD


Discovery of gibberellins

EFFECT OF AMO-1618 ON PETIOLE ELONGATION OF SPINACH


Effect of long days on ga levels in spinach

EFFECT OF LONG DAYS ON GA LEVELS IN SPINACH


Discovery of gibberellins

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

Long Days

Short Days


Discovery of gibberellins

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


Discovery of gibberellins

KINETICS OF GA-INDUCED ELNGATION OF DEEPWATER RICE INTERNODE

30 min


Distribution of cell division following ga treatment of a rosette plant samolus parviflorus

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


Arabidopsis gibberellin response mutants with defects in signal transduction

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

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

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


Discovery of gibberellins

GA acts to block action of both SPY and GAI/RGA

Enzyme involved in protein modification - enhances activity of GAI and RGA


Discovery of gibberellins

THE CEREAL ALEURONE LAYER


Effect of ga on calcium in barley aleurone layer protoplast

EFFECT OF GA ON CALCIUM IN BARLEY ALEURONE LAYER PROTOPLAST

CONTROL + GA3 GA3 + ABA (ABSCISIC ACID)

Low Cytoplasmic [Ca2+] High


Discovery of gibberellins

SUMMARY OF STEPS IN GA SIGNAL TRANSDUCTION PATHWAY


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