Investigation on of Barely Powdery Mildew Virulence Factors in Fars Province, Iran

Determining the pathogenicity factors of barely powdery mildew casual agent is the first step in identifying and producing resistant cultivars. During growing season 2008, ten isolates of barely powdery mildew were collected from different parts of Fars province (Iran). Mass propagated on a barely susceptible cultivar. Seedlings of 19 near-isogenic barley lines, obtained from Palas base type and containing various resistance genes, were inoculated with the collected isolates. A susceptible cultivar (cv. Afzal) was used as positive control. Later on, reactions of lines were recorded according to latent period, type and severity of disease. The detected pathogenicity factors in Fars province seemed to have variable frequencies. Virulence factors against Ml-a3 and Ml-a23 resistance genes were the most abundant in the tested area, while for Ml-K, Ml-a7+Ml-(NO3), Ml-h and Ml-a12+Ml (Em2) genes were the second most abundant. For the Ml-a22 and Ml-a6+Ml-a14 the least frequency of pathogenic potential was observed. There are no pathogenicity factors against Ml-05, Ml-g-Ml-(Cp), Ml-(La), Ml-a8, (Ml-a1, Ml(A12)), Ml-a9, Ml-a10+Ml-(DU2), Ml-a13+Ml-(Ru3), Ml-K(1), Ml-P and Ml-at resistance genes in Fars province. Almost all barley lines followed a similar pattern in their latent period.