Plant hormones Flashcards
What is auxin
A plant hormone which is produced in the roots and shoots
It is produced by meristem
Auxin attributes
Cell elongation
Maintains Apical dominance
Inhibits abscission and fruit ripening
What is apical dominance
Promotes cell elongation but suppresses lateral bud growth
This is because cytokinins assemble with auxin and make apical shoot grow tall but if auxin is cut off then cytokinins can disperse making lateral bud grow
How does cell elongation happen
Auxin produced
Binds to receptors on cell membrane
H+ ion pumped in cell lowering pH
Cell wall becomes flexible
Cell absorbs water making it expand
How is auxin involved in tropisms
In shoot it promotes growth
In root it inhibits growth
If light is coming from one side auxin will accumulate on opposite side making it grow faster so bends towards light
In root it is opposite
It accumulate on lower side making that side grow more
Gibberellins
Promotes stem elongation - taller plants because longer internodes
Germination- energy is released for seedling growth
Abscisic acid
Stops seeds germinating
Promotes stomatal closure
Ethene
Allows fruit ripening
Allows abscission
Commercial use of auxin
Promotes flowering for commercial flower production
Promotes seedless fruit
Commercial use of ethene
Speeds up fruit ripening
Promotes fruit drop in cherry, walnut and cotton
Commercial use of gibberellins
Delays aging of plants
Extends time of fruit or plant being unpicked
