RUSSIAN WHEAT APHID ( Diuraphis noxia ) RESISTANCE IN WHEAT AND RELATED SPECIES

Abstract

The Russian wheat aphid (RWA) has become a crop pest of significant economic importance in wheat-producing areas of North America. Resistant cultivars offer the opportunity for both economic and effective control of this pest. The present study was initiated to identify genes for RWA resistance in wheat and wheat relatives and to assess the expression of the genes in a wide range of genetic backgrounds. Fifty-two lines, including wheat-related species from various geographic regions, synthetic hexaploid wheats, amphiploids derived from Triticum tauschii × T. timopheevii, T. ventricosum × T. turgidum, and hexaploid and octaploid triticales, were evaluated in the greenhouse for resistance to the RWA. There was a close association between leaf chlorosis and leaf rolling, two components of the RWA damage rating system, but the association varied with species. Close relationships were also observed among levels of damage recorded at six rating times for these two indices of RWA resistance. Eighteen entries were resistant to some degree. A high degree of gene expression for RWA resistance was observed in interspecific hybrids indicating that genes conferring resistance in wheat relatives are accessible for use in wheat improvement by established cytogenetic and plant breeding techniques.Key words: Russian wheat aphid, Diuraphis noxia, Triticeae, Agropyron, interspecific hybrids, gene expression