Resistance of Hordeum spontaneum Collected in Israel to Infection with Erysiphe graminis hordei

The progenitor of barley, Hordeum spontaneum C. Koch, is being used extensively for developing improved barley (H. vulgare L.) cultivars. In this study, sites in Israel were identified with H. spontaneum plants resistant or moderately resistant to Erysiphe graminis DC Ex Merat. f. sp. hordei. (Em. Marchal), which incites the disease barley powdery mildew. The sites represent the range of ecological and environmental conditions and of genetic diversity and morphology of plants in Israel. The three cultures of E. graminis hordei, 64.54, 59.11, and R1, used to screen the accessions, possessed the virulence genes corresponding to most of the known resistance genes to that pathogen in barley. Eighty-nine accessions were identified as resistant to all three cultures, and 180 accessions as at least moderately resistant. Sixty-three accessions were resistant to one set of the cultures and moderately resistant to the other cultures suggesting that those accessions may have more than one gene conditioning their resistance. All of the accessions collected in sites in the Galilee, Northern Coastal Plains and Judean Highlands where the pathogen is usually present were resistant or moderately resistant to all three cultures of the pathogen. No resistant or moderately resistant accessions were obtained from sites in the Negev or on Mt. Hermon where the pathogen is seldom observed. Relationships between resistance to E. graminis hordei; genetic diversity and morphology of H. spontaneum plants, and the ecological and environmental conditions at specific sites are being analyzed to identify sites with plants having the maximum disease resistance and genetic diversity. The information will be used in planning future plant germplasm explorations.