GENES FOR RESISTANCE TO RUSSIAN WHEAT APHID IN PI294994 WHEAT

Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is a major economic pest of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) in several western U.S. states. Genetic resistance is an effective strategy for protecting the wheat crop from RWA while minimizing the use of pesticides. The study was conducted to determine the number of genes conferring resistance in the seedling and adult growth stages in the wheat line PI294994 and to establish whether greenhouse and field resistances were related. The resistant line PI294994 was crossed with the club wheat cultivars Moro and Hyak. F2 and F3 seedlings and F, adult plants from the two crosses were artificially infested with RWA and evaluated for their reactions in the greenhouse and field, respectively. Seedling and adult plant reactions indicated that the resistance in the line PI294994 is controlled by two genes. Resistance is conferred by a dominant allele at one locus and by a homozygous recessive allele at the second locus. PI294994 is an effective source of genetic resistance in the field to RWA in the Pacific Northwest.