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Sugar Repression of a Gibberellin-Dependent Signaling Pathway in Barley Embryos
P. Perata1, C. Matsukura, P. Vernieri
1Nagoya University Bioscience Center, Nagoya University, Chikusa-ku, Nagoya 464-01, Japan.
The Plant Cell
|September 19, 2002
Summary
Sugars and hormones interact to control gene expression in barley grains. Carbohydrates repress [alpha]-amylase gene activity in barley embryos but not aleurone layers, indicating complex signaling pathways.
Area of Science:
- Plant Biology
- Molecular Plant Physiology
- Biochemistry
Background:
- Sugars act as signaling molecules influencing plant metabolism and development.
- Evidence suggests sugar signaling interacts with hormonal regulation in plants.
- Gibberellic acid (GA) is a key hormone regulating [alpha]-amylase gene expression in barley.
Purpose of the Study:
- To investigate the interaction between sugars and gibberellic acid in regulating [alpha]-amylase gene expression in barley embryos and aleurone layers.
- To elucidate the specific mechanisms of sugar signaling in this hormonal response.
Main Methods:
- Experiments using barley embryos and isolated aleurone layers.
- Measuring [alpha]-amylase induction by gibberellic acid in the presence and absence of various sugars.
- Testing the effects of glucose analogs and abscisic acid.
Main Results:
- Gibberellic acid-induced [alpha]-amylase expression in aleurone layers is not affected by sugars.
- Carbohydrates effectively repress [alpha]-amylase induction by gibberellic acid in barley embryos.
- [alpha]-Amylase expression in the embryo is localized to the scutellar epithelium and is modulated by both hormones and sugars.
- Glucose effects are independent of gibberellin biosynthesis, osmotic effects, and abscisic acid.
- Only hexokinase-phosphorylatable glucose analogs trigger gene repression, suggesting a metabolic signaling pathway.
Conclusions:
- Hormonal and metabolic signaling pathways interact to regulate gene expression in barley grains.
- Sugar signaling plays a distinct role in modulating gibberellic acid responses within different barley tissues.
- The repression of [alpha]-amylase by glucose in barley embryos involves a metabolic perception mechanism.
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