Virulence Genes and Pathotypes of Puccinia hordei Otth Causing Leaf Rust on Barley in some Areas of Iran

Infected barley leaves were collected from different areas of Iran during 2007-2008 and transferred to the greenhouse at Seed and Plant Improvement Institute in Karaj. After purification and multiplication of spores on susceptible barley cultivar Afzal, 13 selected isolates were evaluated for their virulence genes. Pure spores of each isolate was inoculated separately on the first leaves of 20 near isogenic lines (differentials) in the greenhouse. Based on infection types on leaves, virulence or avirulence factors for different resistance genes(Rph) were determined and eleven pathotypes were identified. Isolate Ard-86-1 with 17 virulence factors was the most virulent and isolate Ard-87-3 with 8 virulence factors was the least virulent pathotypes. The genes Rph 15.ad and Rph 7.g were effective against all 13 isolates, whereas for genes Rph 1.a, Rph 2.b, Rph 3.c, Rph4.d, Rph 6.f + Rph 5, Rph 8.h, Rph 9.i, Rph 10.o, Rph 11.p, Rph 12, Rph 9.z +Rph12, Rph 13.x, Rph 14.ad, Rph 2.j, Rph 2.y and Rph 2.t virulence was detected, and gene Rph 5.e had the lowest virulence frequency. Based on these results, resistance genes being effective against all or the majority of isolates, can be used as the sources of resistance to leaf rust in barley breeding programs in Iran.