Gene discovery and molecular Pre-breeding for insect resistance in wheat and barley

Pre-breeding research has a significant role in linking between genetic resources and breeding as it shortens the time frame between genetic enhancement and the development of new, improved crop varieties. The Russian wheat aphid (RWA), Diuraphis noxia, is one of the most damaging insect pests of wheat and barley throughout the World. Although it is not yet present, its incursion to Australia is expected cause substantial loses to the grains industry and therefore pre-breeding research against this insect is seen as a high priority in Australia. The objectives of the study are to: 1) Identify available RWA resistant wheat and barley germplasm from around the world and characterize against available RWA biotypes in various countries, 2) develop genomic tools for marker-assisted breeding, and 3) introgress new RWA resistance genes into more adapted wheat and barley backgrounds. We have evaluated a wide range of wheat and barley lines from various parts of the world against a number of RWA biotypes from USA, Argentina, Mexico, Hungary, South Africa, France, Chile, Iran, and Syria. Wheat and barley lines with moderate to good levels of resistance were identified. Genetic analysis of RWA resistant wheat lines has revealed significant diversity. To date, with the use of F2 and DH populations we have mapped genes from four new sources of wheat for RWA resistance on chromosomes 1DS and 7D. Closely linked SSR and Diversity array technology (DArT) markers have been identified. These markers are also being used to identify wheat contigs potentially carrying the resistance genes. Introgression of resistance genes to adapted wheat and barley lines have progressed up to BC3 generation. As we have identified some wheat lines that are resistant to both RWA and Ug99 in Kenya, crosses were also established to introgress resistance genes to both pests.