Pathogenic and genetic characterization of six Indian populations of Colletotrichum sublineolum, the causal agent of sorghum anthracnose

Pathogenic and genetic characterization of populations of Colletotrichum sublineolum, the causal agent of anthracnose of sorghum, was done from six Indian locations. Multi-location field evaluation and greenhouse tests were done of 16 sorghum lines that comprised the International Sorghum Anthracnose Virulence Nursery (ISAVN). The lines were tested in a field trial for 4-5 years (1992-1996) at six Indian locations: Indore, Surat, Patancheru, Dharwad, Udaipur and Pantnagar. Plants were scored for disease reaction (R/MR/S) and for disease severity (on a 1-9 scale where 1= no lesion and 9 >75% leaf area covered with lesions) at the soft-dough stage in the field and at the seedling stage in the greenhouse. Significant (P<0.001) differences were observed for virulence (disease reaction) and aggressiveness (disease severity) across locations (isolates) and sorghum lines both in field and greenhouse tests. In both tests isolate x sorghum fine interactions were highly significant (P<0.001) suggesting that populations of C. sublineolum at these six locations were different. A random amplified polymorphic DNA (RAPD) analysis exhibited genetic dissimilarities among the isolates and these were classified in to six groups,