Studies on barley yellow dwarf virus (BYDV) in wheat

BYDV has been one of the major production issues in wheat in high rainfall areas of the southern region including Tasmania, Victoria, and Western Australia. Yellow dwarf virus (YDV) are caused by a range of related luteoviruses but in wheat BYDV-PAV vectored mainly by the oat aphid (R. padi), has been considered the most damaging species worldwide including Australia. Sources of tolerance are thought to be available amongst existing wheat cultivars, but this has not been experimentally validated, nor has the yield advantage been quantified. In our recently GRDC funded project, we will establish one or two sites where infection can be consistent; test current varieties adapted to high rainfall wheat production zones and breeding lines supplied by breeders for BYDV resistance/tolerance; test the impact of the current source of resistance gene Bdv2 derived from intermediate wheatgrass (Thinopyrum intermedium) on yield and grain quality; and provide breeders with useful BYDV tolerance or resistance in a minimum of four grower preferred varieties adapted to high rainfall zones (HRZ). This project will also screen more germplasm for alternative YDV resistance genes. Preliminary yield trials showed a significant reduction in yield due to virus infection. Screening trials in both Australia and China identified a few resistant germplasm. If new genes are found, molecular markers linked to the gene will be identified for use in breeding programs.