Morphological and Molecular Identification of Colletotrichum truncatum Causing Anthracnose on Lentil

Abstract

Anthracnose symptoms observed on lentil (Lens culinaris Medik.) were investigated to identify the causal pathogen and characterize its morphological and molecular features. Field surveys conducted in major lentil-growing regions revealed characteristic symptoms including dark, sunken lesions on stems, pods, and leaves, leading to blighting, premature defoliation, and yield reduction under warm and humid conditions. Fungal isolates obtained from infected tissues produced fast-growing colonies with white to gray mycelium that later turned dark with abundant sporulation on potato dextrose agar. Microscopic examination revealed falcate, hyaline, aseptate conidia consistent with Colletotrichum truncatum. Pathogenicity tests conducted on healthy lentil plants under controlled greenhouse conditions successfully reproduced anthracnose symptoms, confirming virulence and fulfilling Koch’s postulates. Molecular identification using ITS rDNA and β-tubulin gene sequencing confirmed the isolates as C. truncatum, showing high similarity with reference sequences in global databases. Phylogenetic analysis placed all isolates within a well-supported C. truncatum clade, indicating limited but detectable genetic variation among populations from different locations. Minor nucleotide polymorphisms suggested possible adaptation to local agro-climatic conditions and host interactions. Disease severity was strongly associated with high humidity and prolonged leaf wetness, which favored spore germination and infection. The study highlights the importance of C. truncatum as a major pathogen of lentil crops and emphasizes the need for accurate molecular diagnostics for early detection and disease monitoring. Integrated disease management strategies, including use of resistant cultivars, crop rotation, and timely fungicide applications, are recommended to reduce disease incidence and improve lentil productivity.