Agriculture Reference
In-Depth Information
GA
3
triggered
Transcription of
amylase
GA
3
transported
to aleurone
layer
GA
3
Synthesis in
embryo
At
aleurone
Endosperm
Starch
Hydrolysis
Glucose,
Fructose,
Sugars etc.
Α-Amylase
secretion
Fig. 4
GA3 regulated alpha-amylase activity.
In plants, sugars have hormone like activity and modulate
nearly all fundamental processes through the entire life
cycle (Smeekens 2000, Halford and Paul 2003). In cereals, the
process of seedling development is divided into three stages;
imbibitions, germination and seedling elongation (Thomas
and Rodriguez 1994). Sugars regulate this process tightly by
controlling gibberellin (GA) biosynthesis and alpha-amylase
expression, which is essential for the degradation of starch to
provide a nonphotosynthetic carbon source for germination
and seedling development (Yu et al. 1996). After imbibing of
seeds, sugars in embryo are rapidly consumed, leading to sugar
depletion and subsequent activation of alpha-amylase gene
expression during germination (Yu et al. 1996). Meanwhile,
the embryo synthesises GA
3
that are released to aleurone cells
surrounding the starchy endosperm to activate the synthesis
and secretion of alpha-amylase and other hydrolases. The
