IDENTIFICATION OF NEW SOURCES FOR RESISTANCE TO POWDERY MILDEW IN H-SPONTANEUM-DERIVED WINTER BARLEY LINES

Twenty four barley lines derived from the F-7 generation of crosses be tween two winter barley cultivars and different accessions of Hordeum spontaneum Koch collected in Israel were tested against a set of ten E uropean and five Israeli powdery mildew cultures, possessing virulence genes which completely match the spectrum of known mildew resistance genes. The comparison of reaction patterns justified the conclusion th at new genes for resistance have been conferred from H. spontaneum whi ch also differ from genes previously identified in other wild barley a ccessions from Israel. Participation in the expression of the resistan ce reaction of one of the two barley cultivars used in the development of the lines is well documented in some cases. The majority of the li nes was found to be highly resistant against all or almost all Europea n isolates, while various kinds of reactions were observed against the Israeli cultures. The effective transfer of novel mildew resistance f rom H. spontaneum into winter barley confirms similar results with spr ing barley, indicating natural wild barley populations in Israel as a significant gene pool for yet unexploited mildew resistance in barley.