Pathotypes of Colletotrichum capsici, the Causal Agent of Chili Anthracnose, in Thailand

Abstract

Eleven isolates of Colletotrichum capsici were screened on nine chili genotypes derived from four cultivated species of Capsicum: Capsicum annuum, C. baccatum, C. chinense, and C. frutescens. Host reactions were assessed 9 days after inoculation by microinjection of spores into the pericarp of red fruit. A set of disease scales, with 0 to 9 scores, were developed for anthracnose infection of each Capsicum sp. based on percent lesion size in relation to fruit size, appearance of necrotic or water-soaked tissue, and presence of acervuli. Three pathotypes, PCc1, PCc2, and PCc3, were identified according to differential qualitative infection of fruit of C. chinense genotypes PBC932 and C04714. PCc1 was the most virulent pathotype, infecting all genotypes of C. annuum, C. chinense, and C. frutescens, whereas PCc3 was the least virulent pathotype, infecting only the genotypes C. annuum and C. frutescens. Quantitative infection occurred in all chili genotypes except for genotypes of C. baccatum, where no infection occurred, demonstrating various levels of aggressiveness of isolates within pathotypes.