Population Structure of Colletotrichum truncatum in Himachal Pradesh and Identification of Broad-Spectrum Resistant Sources in Capsicum

Abstract

Anthracnose disease of Capsicum caused by Colletotrichum truncatum (syn. C. capsici) is a catastrophic disease causing huge loss in productivity worldwide. Consequently, interest in elucidating its genetic structure has grown in recent decade. In the present study, six random amplified microsatellites were used to access the population structure of 94 isolates of C. truncatum from three agro-climatic zones of Himachal Pradesh. Among the 104 reproducible fragments, 81.73% were polymorphic. Cluster analysis grouped 94 isolates into four groups with no congruence with geographical origin of isolates. Average gene diversity ranged between 0.38 and 0.45, and expected heterozygosity ranged from 0.39 to 0.44. Analysis of molecular variance showed high genetic variability within the zones (99.53%). Screening of 194 genotypes of Capsicum against 94 C. truncatum isolates showed low-level resistance to the fungus. Some promising lines possessing resistance to more than 40 C. truncatum isolates were identified. These genotypes may harbor diverse resistance specificities and can be used to develop anthracnose-resistant genotypes in the State. This is the first resistance evaluation study where Capsicum genotypes were screened individually against a large number of isolates. The results suggest considerable evolutionary potential of pathogen that has enabled it to acquire pathogenicity genes (virulence factors) for infecting diverse host varieties over time and space.