The ApMat marker can resolve Colletotrichum species: a case study with Mangifera indica

Anthracnose disease caused by the Colletotrichum gloeosporioides species complex is a major problem worldwide. In this study, we investigated the phylogenetic diversity of 207 Indian Colletotrichum isolates, associated with symptomatic and asymptomatic tissues of mango, belonging to this species complex. Phylogenetic analyses were performed based on a 6-gene dataset (act, cal, chs1, gapdh, ITS and tub2), followed by ApMat sequence-analysis. The ApMat-based phylogeny was found to be superior as it provided finer resolution in most of the species-level clades. Importantly, the ApMat marker identified seven lineages within C. siamense sensu lato, including C. jasmini-sambac, C. hymenocallidis, C. melanocaulon, C. siamense sensu stricto and three undesignated, potentially novel lineages. In this study, C. fragariae sensu stricto, C. fructicola, C. jasmini-sambac, C. melanocaulon and five undesignated, potentially novel lineages were found to be associated with mango tissues. There is a need to develop a consensus among mycologists as to which genes should be used to define and delimit a Colletotrichum species and in the mean time mycologists should voluntarily restrain from describing new species based on inadequate datasets.