Virulence Genes and Pathotypes of Puccinia striiformis f. sp. hordei Causing Yellow Rust on Barley in some Areas of Iran

To identify the barley yellow rust pathotypes، yellow rust samples of were collected from barely، wild barley (Hordeum morinum) and wheat in different provinces of Iran. Isolates were identified as P. striiformis f. sp. hordei or P. striiformis f. sp. tritici based on virulence on barley or wheat differential seedlings، respectively. Virulence factors and pathotypes of barley yellow rust were determined based on avirulence/virulence formula. Totally، ten pathotypes were identified in this study، of which seven were new pathotypes for the world. Some of pathotypes may be the result of hybridization between the two formae speciales، since they exhibited virulence on a number of wheat differentials and triticale in addition to barley differentials. The pathotypes PSH-87 and PSH-84 with six virulence factors had the widest virulence spectrum and two pathotypes PSH-51 and PSH-85 with three virulence factors had narrow virulence spectrum. None of the pathotypes had virulence on resistance genes rpsEm1 and rpsEm2 and only one pathotype had virulence on each of resistance genes Rps4 (Yr4)، rpsHF، rpsVa1، rpsVa2 and Rps1. c. The highest virulence frequency was determined for genes rpsHi1، rpsHi2 (0. 83%) and rps2 (0. 67%). The genes which were effective against all or majority of pathotypes can be used as resistance sources in breeding programme for cotrolling barley yellow rust.