MULTILOCUS GENE PHYLOGENY REVEALS OCCURRENCE OF COLLETOTRICHUM CYMBIDIICOLA AND C CLIVIAE ON ORCHIDS IN NORTH EAST INDIA
P. Chowdappa, C.S. Chethana, R.P. Pant, P.D. Bridge
The causal organism responsible for severe outbreaks of orchid anthracnose in India, which affectes leaves, petioles and blooms, is not clearly established. Ten Colletotrichum isolates recovered from different orchid species in the Sikkim state were characterized based on morphological and a multilocus molecular phylogenetic analysis of the rDNA-ITS region (ITS), partial actin (ACT) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) sequences. Phylogeny inferred from combined datasets of ACT, ITS and GAPDH revealed two groups, representing Colletotrichum cymbidiicola and C. cliviae. Cultural and morphological characters are presented for these two species. Pathogenicity assays confirmed that both species isolated from orchids are the causal agents of anthracnose. The occurrence of C. cymbidiicola and C. cliviae is reported for the first time on orchids in India.