Optimizing preharvest sprouting tolerance in malting barley

麦芽大麦是加拿大最重要的经济作物之一，它的生产受到一系列环境胁迫因素的不利影响，例如导致收获前发芽(PHS)的环境因素，PHS指的是收获前母株上的谷物萌发。穗发芽降低了作物的等级，使谷物不适合制麦，给生产者造成了很大的经济损失。因此，加拿大啤酒大麦生产商对具有最佳休眠水平的品种的需求很高，这些品种可以防止田间发芽的风险，同时允许收获后快速萌发。种子中表现出的休眠(PHS耐性)水平通常由植物产生的低含量化合物控制，这些化合物通常被称为“植物激素”，其中脱落酸(ABA)和赤霉素(GA)是主要的参与者。ABA促进种子休眠的诱导和维持，GA促进种子萌发/萌发。然而，在啤酒大麦中，控制种子ABA水平和反应的分子和遗传因素及其与促进发芽的GA的拮抗作用，从而维持最佳休眠的分子和遗传因素还知之甚少。本研究的目的是找出控制种子ABA水平和反应的特定的ABA相关遗传元件，并研究ABA对种子GA水平和反应以及淀粉降解的调节。这一研究结果将为加快培育具有最佳休眠状态的啤酒大麦品种提供分子和遗传工具，以防止PHS，提高啤酒大麦的产量和质量，从而为加拿大啤酒大麦生产者带来最大的经济效益。这项研究还支持培训高素质的作物生物技术和分子育种人员，这对确保加拿大农作物行业的竞争地位至关重要。

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.