Hormonal regulation of preharvest sprouting in wheat

作为加拿大重要的经济作物之一，小麦的生产受到各种压力因素的阻碍，包括收获前的潮湿条件，导致谷物在穗上发芽，称为收获前发芽（PHS）。小灵通造成粮食产量和质量的损失，给小麦生产者带来了高昂的成本。籽粒对小灵通的耐受程度主要由脱落酸（ABA）和赤霉素（GA）之间的平衡调节，而脱落酸和赤霉素是植物产生的影响生长和发育过程的化合物之一，通常被称为“植物激素”。ABA促进小灵通耐受性，GA促进萌发，两者的比值受其产生和降解过程的影响。ABA / GA比值较低的种子小PHS潜力增大。相反，种子ABA / GA比值越高，小灵通耐受性越强。在其他植物物种中已经发现了ABA和GA水平平衡调节的几种策略和调控元件。然而，关于这两种激素如何共存并相互作用调节小麦籽粒对小灵通的耐受性，人们知之甚少。本研究的目的是确定调节小麦ABA产生的特定元件，并研究它们在控制小麦籽粒GA和小灵通耐受性水平中的作用。本研究结果将为培育耐小灵通小麦品种提供有力的工具；从而提高小麦的产量和质量，以及加拿大小麦生产者的农业收入。此外，这项研究涉及培训作物生物技术领域的高素质人员，这对加拿大作物工业的竞争力至关重要。

The production of wheat, one of the major economically important crops of Canada, is hampered by a variety of stress factors, including wet conditions prior to harvest that cause grains to germinate while still on the spike, termed as preharvest sprouting (PHS). PHS causes loss in grain yield and quality, incurring a high cost for wheat producers. The degree of grain tolerance to PHS is regulated mainly by the balance between abscisic acid (ABA) and gibberellins (GA), which are among the plant produced compounds that influence growth and developmental processes at very low concentrations, usually coined as "plant hormones". ABA promotes PHS tolerance whereas GA enhances germination, and the ratio between these two hormones is modulated by changes in their respective production and degradation processes. Seeds with a low ABA to GA ratio exhibit increased potential for PHS. By contrast, a high ABA to GA ratio in seeds leads to increased PHS tolerance. Several strategies and regulatory elements involved in the modulation of the balance between the levels of ABA and GA have been identified in other plant species. However, very little is known about how the two hormones coexist and interact in regulating the tolerance of wheat grains to PHS. The goal of this research is to identify specific elements that regulate ABA production in wheat, and investigate their role in controlling the levels of GA and PHS tolerance in the grains. The findings of this research will provide powerful tools to develop wheat cultivars with adequate PHS tolerance; thereby improving wheat yield and quality, and farm income for Canadian wheat producers. Further, this research involves the training of highly qualified personnel in the area of crop biotechnology, which is critical to the competitiveness of Canada's crop industry.