INHERITANCE OF RESISTANCE TO HESSIAN FLY IN RYE AND IN WHEAT RYE TRANSLOCATION LINES

Rye, Secale cereale L., is an important genetic resource for resistance to Hessian fly, Mayetiola destructor (Say). Resistance genes have been transferred from 'Chaupon' rye chromosome arm 2RL and 'Balbo' rye chromosome arm 6RL to common wheat (Triticum aestivum L.) via wheat-rye chromosomal translocations. Our objectives were to determine (i) the number of resistance genes in Chaupon and Balbo and their allelic relationships, and (ii) the mode of inheritance of resistance in the wheat-rye translocation lines. Several crosses were tested in a greenhouse for reaction to Biotype L of Hessian fly. Analyses of F2 populations showed that Chaupon and Balbo each segregated for two independent dominant genes exhibiting duplicate epistasis. All genes conditioned antibiosis to first-instar larvae. One of the genes in Chaupon expressed a chlorotic lesion reaction in response to larval feeding and was different from the genes in Balbo. When this gene occurred together with genes that did not cause expression of chlorotic lesions, F2 plants segregated in modified ratios of 12 resistant plants without lesions: 3 resistant plants with lesions: 1 susceptible plant. Crosses of T2BS.2RL translocation line with susceptible wheat 'Karl' showed that resistance from Chaupon chromosome arm 2RL was inherited as a single dominant factor and that 2RL carries the gene that expresses chlorotic lesions. Crosses of Ti4AS-4AL-6RL-4AL translocation lines with susceptible wheat 'TAM106' showed that resistance from the Balbo 6RL segment was inherited as a single dominant factor. These results demonstrate that the wheat-rye translocations can be utilized efficiently for incorporating Hessian fly resistance into wheat.