Characterization of Colletotrichum species causing new pre-harvest anthracnose symptoms on mango in Eastern India

Anthracnose caused by Colletotrichum species is an important disease of mango (Mangifera indica L.) affecting leaf, flowers and fruits in mango orchards worldwide. The fungus Colletotrichum sp. usually invade the fruits during its developmental stage but remains quiescent until fruit ripening culminating in devastating anthracnose disease, especially during post-harvest stage. In contrary, new kind of pre-harvest anthracnose symptoms were observed on green unripe mangoes with varying level of incidence at field level in the state of Odisha, situated in Eastern India. This study attempted to characterize the Colletotrichum species affecting mango cultivars and causing new kind of symptoms under field condition on maturing green mangoes in comparison to post-harvest phase using morphological methods and molecular tools as well as by pathogenicity tests on intact green as well as on detached mature fruits. Eight Colletotrichum isolates from pre-harvest phase and two from post-harvest phase isolated from different mango varieties were studied for their diversity through morphological examination as well as sequence analysis of internal transcribed spacer (ITS), chitin synthase (CHS-1), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-tubulin (TUB2) and ApMat genomic regions. Multigene phylogeny of all ten isolates revealed the identification of C. siamense. Pathogenicity assay of all 10 Colletotrichum isolates on green intact fruits in field as well as on detached ripening fruits in laboratory resulted in similar anthracnose symptoms on two selected test varieties Arka Anmol and Mallika. Results confirmed the association of C. siamense with both pre as well as post-harvest anthracnose symptoms of mango. Accurate pathogen identification provides a reliable basis for devising disease management schedules against anthracnose occurring at different phenological stages of the mangoes.