Development of hormone based genomic tools to accelerate wheat breeding for enhanced preharvest sprouting tolerance

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Wheat is one of the most economically important crops of Canada, however, its production is challenged constantly by a variety of stress factors such as preharvest sprouting (PHS), which refers to the germination of grains on the mother plant prior to harvest. PHS lowers grain yield and severely limits end-use quality, causing substantial economic loss to the producers. Given that the incidence of PHS is expected to increase with climate change induced seasonal shifts in precipitation and temperature, tolerance to PHS is a highly desirable trait sought by Canadian wheat producers. Many of the genetic and environmental factors that regulate PHS tolerance are mediated mainly by 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 and GA play antagonistic roles in controlling PHS; ABA enhances PHS tolerance while GA promotes PHS potential. However, how environmental factors such as temperature regulate the balance of grain ABA/GA levels and sensitivity during maturation, and thereby PHS tolerance is poorly understood in wheat. Difference in PHS tolerance between wheat genotypes can also be induced by variations in the genomic sequences and/or expression levels of key genes implicated in the control of PHS. The goals of this research are to identify specific molecular elements that regulate temperature-induced changes in ABA/GA balance in maturing wheat grains, identify PHS associated variations in the sequences of ABA related genes, and investigate temperature regulation of other key PHS controlling genetic factors. The findings of this research will provide powerful genomic tools that can facilitate the breeding of 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 and molecular breeding, which is critical to the competitiveness of Canada's crop industry.