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Oxalate oxidases and differentiating surface structure in wheat: germins.
1Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A8.
The Biochemical Journal
|June 22, 2000
Summary
Oxalate oxidases (OXOs) in wheat, like germin and pseudogermin, are concentrated in surface tissues, potentially aiding in defense and differentiation. Their activity requires specific pre-treatments for detection.
Area of Science:
- Biochemistry
- Plant Science
- Molecular Biology
Background:
- Oxalate oxidases (OXOs) are enzymes found in cereal crops.
- Germin and pseudogermin are specific OXOs concentrated in wheat's surface tissues.
- These enzymes play roles in plant development and defense mechanisms.
Purpose of the Study:
- To investigate the localization and potential functions of oxalate oxidases (OXOs) in wheat.
- To explore the role of OXOs in the differentiation of wheat grain structures.
- To characterize OXO activity and its dependence on pre-treatment.
Main Methods:
- Localization studies of germin and pseudogermin in wheat embryos and grains.
- Comparative analysis of OXO expression and oxalate concentration across different cereal species.
- Biochemical assays to measure OXO activity, including pre-treatment protocols.
Main Results:
- OXO-psi accumulates in wheat epidermis, preceding the development of the tough grain shell.
- Major crop cereals exhibit similar oxalate levels but varied OXO expression.
- Wheat OXO activity was detected only after specific pre-incubations, such as with pepsin or cell-wall polysaccharides.
Conclusions:
- Germin-like OXOs in wheat surface tissues may contribute to programmed cell death and barrier formation against predators.
- The unique stability of germin-like OXOs is specific to major crop cereals.
- Novel methods for OXO assay revealed that pre-treatment is crucial for detecting activity in wheat extracts.