Poster Session: Systematics/Evolution/Ecology-Fungi

81-P

Genetic characterization of virulence/avirulence genes of Puccinia striiformis f. sp. tritici.
M. Wang (1), A. Wan (1), X. CHEN (2)
(1) Department of Plant Pathology, Washington State University, Pullman, WA, U.S.A.; (2) USDA-ARS, Pullman, WA, U.S.A.

Common barberry (Berberis vulgaris) was recently found as an alternate host for Puccinia striiformis f. sp. tritici (Pst), the causal agent of wheat stripe rust. Young barberry leaves were inoculated with teliospores produced from adult wheat plants of wheat infected with urediniospores from a single-uredium isolate (PST-127) under controlled conditions. Aeciospores produced on barberry leaves were inoculated on seedlings of wheat line ‘Avocet Susceptible’ (AvS). A total of 19 single-uredium isolates were obtained. The virulence and avirulence of the 19 isolates and the parental isolate were tested on wheat lines used as Pst race differentials or carrying a single Yr gene. Virulences to Yr1, Yr2, and Yr9 and avirulences to Yr5, Yr15, Yr24, Yr32, and YrSP were homozygous and virulences to other genes were segregating. Virulence or avirulence to other 14 Yr genes segregated at 1:1 ratio for a single locus (P, 0.05-0.89), except those to Yr17 and Yr43. Ten virulences (to Yr6, Yr7, Yr8, Yr19, YrUkn, Yr27, Yr43, Yr44, YrExp2, and YrTye) and four avirulences (to Yr10, Yr17, YrExp1, and YrTr1) appeared to be dominant. This is the first genetic study for characterizing Pst virulence and avirulence genes and demonstrating the gene-for-gene relationship for avirulence and resistance genes in the Pst-wheat pathosystem. More experiments are conducted to enlarge the segregating Pst population and mapping the segregating virulence/avirulence loci.
Keywords: Fungus, Cereals-Grains, Wheat