Morphological, pathological and molecular variability in Colletotrichum capsici, the cause of fruit rot of chillies in the subtropical region of north-western India

Fruit rot of chillies (Capsicum annuum L.), caused by Colletotrichum capsici under tropical and subtropical conditions, results in qualitative and quantitative yield losses. Based on variation in cultural and morphological traits of C. capsici populations, 37 isolates were categorized into five groups designated, respectively, as Cc-I, Cc-II, Cc-III, Cc-IV and Cc-V. In culture, most of the isolates produced cottony, fluffy or suppressed colonies. However, no significant differences were noticed in shape and size of conidia. The reaction of the 37 isolates on an indigenously developed differential set of Capsicum cultivars indicated the existence of different virulences in Himachal Pradesh (HP) chilli populations. Fifteen pathotypes of the pathogen were characterized from various chilli-growing regions of HP. Pathotype CCP-1 was most virulent and attacked all the differential cultivars. The genetic relationship between five morphological groups recognized within C. capsici was investigated using random amplified polymorphic DNA (RAPD) analysis. Molecular polymorphism generated by RAPD confirmed the variation in virulences of C. capsici and different isolates were grouped into five clusters. However, four isolates (Cc-5, Cc-33, Cc-29 and Cc-37) exhibited identical RAPD haplotypes. The pathological and RAPD grouping of isolates suggested no correlation among the test isolates.