Genetics of Pathogenicity of Wheat Stem Rust Pathogen (Puccinia Graminis F.Sp. Tritici) and Reaction of Wheat Genotypes to the Disease

Pathogenicity of wheat stem rust was investigated during two cropping seasons of the years 2010 and 2011. towards this end, 47 isogenic lines of wheat stem rust along with 43 cultivars/lines of the crop were tested in field conditions (natural infection) and also in the greenhouse conditions. The results showed, similarity of pathogenicity for plants carring gene/s Sr7B, Sr8A, Sr8B, Sr9B, Sr9D, S9G, Sr11, Sr13, Sr16, Sr17, Sr25, Sr34 and SrDP2 as for two isolates. As for the in genetic variation of two wheat stem rust isolates (in greenhouse conditions), Kelardasht isolate did not show virulence for 15 isogenic lines carrying gene/s Sr5, Sr8A, Sr22, Sr24, Sr26+Sr9G, Sr27, Sr28, Sr29, Sr31, Sr32, Sr33, Sr35, Sr36, SrGT and SrWLD. From Dashte-Azadegan isolate of Khuzestan, virulence for gene Sr31 as a variant of Ug99 race was detected, while this isolate being avirulent on plants carrying gene/s Sr5, Sr22, Sr24, Sr26+Sr9G, Sr27 and SrGT. The results of evaluation of resistance for commercial wheat cultivars and elite lines indicated that, such new released cultivars as Morvareid, Sivand and Parsi were resistant with a range of reaction of 5R-50M to stem rust diseases as observed during the two years of the study.