Study on pathotype diversity and virulence factors of Puccinia striiformis f.sp. tritici, the causal agent of wheat yellow rust in Iran

Yellow rust is one of the most important diseases of wheat that the pathogen populations have many pathotypies in different environmental conditions and during different years. This study was conducted to identify the pathotypes of wheat yellow rust in different environmental conditions and during two successive years. In spring of 2008 and 2009, 29 isolates of wheat yellow rust leaves were collected from different parts of Iran base on the dispersion and the different environmental conditions. Urediniospores of collected leaves were multiplied on Bolani under greenhouse conditions and then pathotypes, virulence factors and frequency were detected base on inoculated differential sets responses to each isolates. Among 29 collected isolates, 19 pathotypes were identified. In some regions similar pathotypes observed including 6E2A+, 6E6A+, 6E130A+ and 6E150A+. In 2008, the most and the least virulence potency related to isolates Ahvaz2 and Gharakhil that could overcome 12 and 5 resistance genes of the host plant, respectively. In 2009, the most and the least virulence potency related to isolates from BayekolaII, ToroghII, Borojerd and ZarghanII that could overcome 10 and 4 resistance genes of the host plant, respectively. In two years, the majority of isolates with a high frequency percent showed virulence on plant/s with Yr2, Yr2+, Yr7, Yr7+ and YrA genes. No virulence was detected on plant/s with Yr 1, 3, 4, 5, 9+, 10, 15, CV, SP, SU and ND genes. Considering the fact that no virulence was detected for plant/s with Yr1, Yr3, Yr4 and Yr10 genes, these genes can be used in wheat breeding programs in all regions of Iran to control wheat yellow rust.