GENETIC AND CYTOGENETIC ANALYSES OF RUSSIAN WHEAT APHID RESISTANCE INTRITICALE X WHEAT HYBRIDS AND PROGENIES

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is a serio us pest in wheat (Triticum aestivum L,), Four Russian triticale (X Tri ticosecale Wittmack) lines, PI 386148, PI 386149, PI 386150, and PI 38 6156, have been the most resistant triticales to the RWA in several sc reening tests. Resistance is controlled by a single dominant gene at a common locus in the three triticale lines PI 386148, PI 386149, and P I 386156. However, expression of these resistance genes in a wheat bac kground and the inheritance of resistance in PI 386150 have not been d etermined. The objectives of this study were (i) to assess the transmi ssion and the expression of RWA resistance in triticale x wheat hybrid s, (ii) to determine the inheritance of resistance in PI 386150, and ( iii) to identify the rye chromosome(s) from Secale montanum Guss. asso ciated with RWA resistance. Advanced generations from crosses between PI 386148 triticale x 'Lamar' wheat and PI 386150 triticale x Lamar we re produced and the progenies screened to determine their reaction to the RWA. All F-1 plants derived from both crosses were resistant indic ating that resistance is dominant in both triticale lines. C-banding a nd in situ hybridization with the pSc119.1 probe, a rye-specific DNA p robe, showed that chromosome 4R(mon) was associated with resistance in PI 386150. The results of this study should facilitate the transfer o f the resistance gene(s) from these triticale lines into wheat.