Genomics and Heterosis in Hexaploid Wheat

Wheat is the most widely grown crop, occupying 17% of all the cultivated land. Exploitation of heterosis though development of hybrid wheat is one of the most attractive options to increase the wheat productivity, but the underlying mechanism remains largely unknown. Recently, attempts have been made for last decade to understand genetic and molecular basis of heterosis in wheat. At the genomic level, total heterozygosity across the whole genome is not as important for phenotypic expression as heterozygosity of some specific tracts especially regions bearing QTLs for different traits. At the level of gene expression complex networks specific for different developmental stages and tissues were monitored, and these results indicated that the hybridization between two parental lines can cause expression changes of different genes. The accumulation of dominance and partial dominance expression in wheat hybrid could be a major determinant of root heterosis, and the alteration of GA biosynthesis and response pathway might be responsible for the observed heterosis in plant height.. In addition, higher photosynthetic capacity and water use efficiency could be one of the important physiological basis of wheat hybrid vigor.