Molecular and phenotypic characterization of Colletotrichum plurivorum and Colletotrichum musae causing banana anthracnose disease in the Central Province of Sri Lanka

Abstract

Most of the commercial banana cultivars in Sri Lanka are susceptible to anthracnose disease. Colletotrichum musae has been known as the causal agent of banana anthracnose for decades and the pathogen has been identified using morphological characteristics. Molecular analyses based on multigene phylogenetics are now standard protocols to identify Colletotrichum species. The present study was aimed at identifying Colletotrichum species causing banana anthracnose by molecular and phenotypic characterization. Thirty-seven isolates were obtained from ripened bananas showing anthracnose symptoms, collected from different locations in the Central Province of Sri Lanka. Of them, 36 were preliminarily identified as Colletotrichum based on conidial morphology. The remaining isolate did not sporulate during the entire study period. Ten isolates taken for molecular studies consisted of eight with orange/white arial mycelia and orange conidial masses, one with a white to greyish colony and blackish clusters of ascomata, and one with a white to faint pink colour colony. DNA extracted from each isolate was subjected to multi-gene DNA sequence analysis using ITS, TUB, GAPDH and GS loci. Based on phylogenetic analyses, eight isolates were identified as Colletotrichum musae, and the other two as C. plurivorum and C. siamense. The vegetative morphology of C. plurivorum differed considerably from C. musae and C. siamense. Slight differences in colony morphology were observed among the C. musae isolates. Freshly harvested healthy bananas were artificially inoculated with isolates of C. musae or C. plurivorum and produced typical anthracnose lesions within a week. The Colletotrichum siamense isolate failed to develop anthracnose symptoms. This is the first report of C. plurivorum causing banana anthracnose.