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HORMONE PHYSIOLOGY AND
SIGNAL TRANSDUCTION
Huseyin Tombuloglu, Phd.
GBE 304 Spring 2015
GIBBERELLINS
Gibberellins have a number of effects on plant
development. They can:
stimulate rapid stem and root growth,
induce mitotic division in the leaves of some plants,
 increase seed germination rate.
elongates plant internodes
Functions of Gibberellins
 Cell enlargement and cell divisions in sub-apical
meristems.
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Growth in stems, fruits, and leaves.
Stem and leaf expansion.
Fruit development and expansion.
Stimulation of flowering
Cell divisions in some tissues.
Dormancy and senescence.
Seed germination.
Functions of Gibberellins
Functions are similar to auxins, but GA has a
much different chemical structure.
Gibberellins cause cell expansion and cell
divisions in sub-apical meristems.
Interesting to note:
Gibberellins applied to whole plants will increase or
promote growth and expansion, but auxins applied to
whole plants usually inhibit growth….what results is a
concentration problem.
Cabbage can be induced to
bolt and flower by
applications of GA3
Figure 20.4 Gibberellin induces growth in “Thompson Seedless” grapes