Physiologic Specialization of Puccinia hordei in Israel from 1983 to 1985

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Abstract
In Israel, the rust pathogen Puccinia hordei annually attacks indigenous wild Hordeum species and cultivated barely. The sources of primary inoculum are indigenous alternate hosts, Ornithogalum spp. Studies on physiologic specialization of 299 rust cultures isolated from 1983 through 1985 revealed 67 virulence patterns. Some highly virulent cultures were of countrywide occurrence. Gene Pa7 offered protection against over 99% of the cultures, while genes Pa3 and Pa9 were effective against 47.16 and 42.8%, respectively. The overall virulence situation of cultures obtained during 1983-1985 deviated insome aspects from that of previous years. This could be seen in differences of the order of ranking of the virulence patterns as well as in the appearance of new virulence spectra. Assumably, the virulence situation of P. hordei is dynamic as a result of genetic recombination in the commonly occurring gametophytic stage of the fungus on widespread Ornithogalum spp.