Species Diversity, Virulence, and Pathogenicity of Colletotrichum spp. Associated with Anthracnose on Pepper

Abstract

Species diversity, virulence, and pathogenicity of Colletotrichum spp. associated with anthracnose disease of pepper (Capsicum spp.) were investigated to elucidate pathogen complexity and disease severity relationships. Field surveys were conducted in pepper-growing regions, and symptomatic fruits and leaves exhibiting typical sunken lesions and necrotic spots were collected for fungal isolation. Morphological characterization based on colony traits, conidial shape, and appressorial formation was complemented with molecular identification using ITS rDNA sequencing for accurate species delimitation. Results revealed the presence of multiple Colletotrichum species complexes, indicating a highly diverse pathogen population associated with anthracnose incidence. Pathogenicity assays on detached pepper fruits demonstrated significant variation in virulence among isolates, with certain strains producing rapidly expanding lesions and higher disease severity indices. In contrast, other isolates exhibited moderate to low aggressiveness, suggesting differential host–pathogen interaction mechanisms. Molecular phylogenetic analysis supported clear clustering of isolates into distinct clades corresponding to species-level differentiation, reinforcing the presence of cryptic diversity within the pathogen population. Virulence variability was strongly correlated with lesion expansion rate and sporulation capacity, highlighting the epidemiological importance of highly aggressive strains in disease outbreaks. The study emphasizes the need for integrated morphological and molecular approaches for precise identification of Colletotrichum spp. and for effective disease management strategies. These findings contribute to understanding anthracnose epidemiology and support the development of resistant pepper cultivars and targeted control measures to reduce yield losses.