Molecular phylogeny-based identification of Colletotrichum endophytica and C. siamense as causal agents of avocado anthracnose in Sri Lanka

Avocado (Persea americana) is a sub-tropical fruit with high nutritional value and numerous health benefits. Among the postharvest fungal diseases that affect ripe avocados, anthracnose is one of the most destructive disease worldwide, causing significant postharvest fruit losses and limiting shelf life. Over 15 Colletotrichum species have been reported as causing avocado anthracnose from avocado growing countries in the world. In the present study, 35 Colletotrichum isolates were obtained from ripe avocados showing anthracnose symptoms, collected from the Central and North Western Province of Sri Lanka. Fifteen randomly selected isolates were subjected to DNA sequence analysis using ITS, TUB2, and GAPDH regions. Species affiliations and identities of the resulting sequences were determined through similarity-based searches of the NCBI GenBank Database. Based on the combined phylogentic analysis of three gene regions, nine and six isolates were identified as C. endophytica and C. siamense respectively, both belonging to the C. gloeosporioides species complex. Of the two species, C. endophytica is reported as a causal agent of avocado anthracnose for the first time.