در ايران ASCOCHYTA RABIEI تعيين گروه بيماريزايي جدايه هاي قارچ

Pathotyping of Ascochyta rabid isolates in Iran

Pathogenicity of twenty-six isolates of ascochyta blight fungus, Ascochyta rabiei, from 16 provinces of Iran was evaluated using 16 differential cultivars in greenhouse condition, Variance analysis revealed that affect of isolates, cultivars and their interaction were significant. Isolates were grouped on the basis of pathogenecity pattern, virulence intensity and cluster analysis. Pathogenecity test identified three races (R1, R2, and R3) and two pathotypes (P1, P2), but on the base of virulence intensity all the isolates were divided into three pathotypes (P1, P2, P3). Cluster analysis distinguished two virulence groups with the averages 6.21 (highly virulence) and 3.87 (weakly virulence). In the study, a new method was used for pathotyping of isolates. At first, the cultivars divided into six resistance levels then all the isolates resolved into six pathotypes (PI, P2, P3, P4, P5, P6). The new method had more ability for grouping of isolates. The results showed Pathotype 6, includes three isolates from Tabriz, Markazi and Hamedan provinces, is very aggressive and all the used cultivars are sensitive against it. Thus it looks that it is necessary to design programs for breeding resistance lines in different areas.