CHARACTERISATION OF STEM RUST AND STRIPE RUST SEEDLING RESISTANCE GENES IN SELECTED WHEAT CULTIVARS FROM THE UNITED KINGDOM
D. Singh, R.F. Park, R.A. McIntosh, H.S. Bariana
Sixty five wheat cultivars grown in the United Kingdom were characterised for seedling stem rust and stripe rust resistance genes using Australian pathotypes of Puccinia graminis f. sp. tritici and Puccinia striiformis f. sp. tritici, respectively. The studies detected eight stem rust resistance genes (Sr5, Sr8a, Sr9g, Sr12, Sr30, Sr31, Sr36 and Sr38) and seven stripe rust resistance genes (Yr1, Yr6, Yr7, Yr9, Yr17, Yr27, YrHVII) either singly or in combinations, among which the linked genes Sr31 and Yr9 were the most common. The stem rust resistance genes identified have limited breeding value in Australia and world-wide because virulence for all occurs in many geographical areas. However, for stripe rust resistance, several cultivars represent potentially new sources of resistance. Resistance in these cultivars may be due to uncharacterised resistance gene(s) or gene combination(s) that could not be resolved with the array of pathotypes used. The information presented, when combined with previous characterisation of leaf rust resistance genes in these cultivars, is useful for plant breeders in rationalising germplasm enhancement programs.