Optimizing preharvest sprouting tolerance in malting barley

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The production of malting barley, one of the most economically important cereal crops of Canada, is adversely affected by a range of environmental stress factors such as those causing preharvest sprouting (PHS), which refers to the germination of grains on the mother plant before harvest. Preharvest sprouting decreases crop grade and makes the grains unsuitable for malting and this incurs high economic loss to the producers. Therefore, cultivars with optimal level of dormancy that prevents the risk of field sprouting while allowing rapid germination after harvest is in high demand by Canadian malting barley producers. The level of dormancy (PHS tolerance) manifested in seeds is known to be controlled by the low-abundant plant-produced compounds often referred as "plant hormones", of which abscisic acid (ABA) and gibberellin (GA) are the major players. ABA enhances the induction and maintenance of seed dormancy while GA promotes seed germination/sprouting. However, the molecular and genetic factors controlling seed ABA level and response and its antagonistic interaction with the sprouting promoting GA, and thereby the maintenance of optimal dormancy is poorly understood in malting barley. The goals of this research are to identify specific ABA related genetic elements that control seed ABA level and response, and investigate ABA regulation of seed GA levels and response, and starch degradation, a process induced by sprouting. The findings of this research will provide molecular and genetic tools that can accelerate the breeding of malting barley cultivars with optimal dormancy to prevent PHS and enhance the yield and quality of malting barley, which in turn maximizes the economic returns for Canadian malting barley producers. This research also supports the training of highly qualified personnel in crop biotechnology and molecular breeding, which is critical for ensuring the competitive position of Canada's crop industry.