Japanese farmers noticed
abnormal growth of young infected rice plants they called “Bakanae or foolish seedling” causative agent
was fungus Fusarium moniliforme, the
imperfect stage of Gibbbereella
fujikuroi of Ascomycetes.
Named as GA1,
GA2,GA3…
Most
significant and well studied GA3- GA1 – in elongation
- GA9- in flowering
- Gibberellins distribute throughout the plant kingdom in ferns, mosses
- GA5 is responsible for ‘super elongation’ disease of Cassava.
Mobilization of
reserve food, How?
- Events in barley seed germination
- Embryo is activated by imbibitions of water
- Gibberellin is produced in the embryo
- It diffuses into the aleurone layer
- Then induces synthesis of digestive enzymes α-amylase, protease
- Enzyme converts starch to sugars and proteins to aminoacids including tryptophan
- Tryptophan thus produced is translocated to the coleoptiles tip
- There it is converted to IAA
- IAA moves from the coleoptiles tip to the base
- Coleoptiles cell wall become weakened
- Water is taken up and cell enlarges
Major Effects
Stem elongation
Stem elongation
Elongation of dwarf plants (Rosette plants)
Promote flowering
Synthesis of auxin by Gibberellin?
Gibberellin>protease->protein->tryptophan->auxin
- Induce parthenocarpy
- Breaking dormancy
Transport:
non-polar through phloem
What are Anti Gibberellins?
- Compounds interfere with Gibeberellin biosynthesis
- eg: (2-chloroethyl) tri methyl ammonium chloride or cycocel (CCC), phosphon-D and alar
Tags:
Bakanae
bolting
cycocel (CCC)
foolish seedling
Fusarium moniliforme
GA3
plant hormone
What are Anti Gibberellins?
