Identification, prevalence and pathogenicity of Colletotrichum species associated with chilli anthracnose in India

Anthracnose of chilli caused by a complex of Colletotrichum species causes significant yield losses by causing both pre- and post-harvest fruit decay. To understand the diversity of Colletotrichum in India, phylogenetic analysis of 115 Colletotrichum isolates, based on ITS and TUB2 sequences separated Colletotrichum isolates into 4 major species complexes (SC), i.e., truncatum SC (70 isolates), gloeosporioides SC (39 isolates), orchidearum SC (4 isolates) and boninense SC (2 isolates). Two isolates were selected among those preliminary identified to be analyzed further with CHS1, ACT, GAPDH and CAL genomic regions and found C. truncatum, C. gloeosporioides, C. siamense, C. fructicola, C. karstii and C. plurivorum. In pathogenicity tests on unwounded plants, all Colletotrichum spp. identified in this study were able to cause lesions on chilli and papaya but were non-pathogenic to tomato and cotton. The findings provide information on the distribution and prevalence of Colletotrichum spp. in India, crucial for deployment of effective integrated pest management strategies and for resistance breeding. The results also suggest that Colletotrichum spp. are opportunistic pathogens that can cause considerable damage to non-host crops.