Colletotrichum species from Jasmine (Jasminum sambac)

Abstract

Colletotrichum species associated with leaf and flower anthracnose of jasmine (Jasminum sambac) in the Ho Chi Minh region of Vietnam are reported. The disease of jasmine plantations was considered serious as it likely reduced flower yield. Leaves were colonized by Colletotrichum species which formed chlorotic regions with light brown necrotic centres, which eventually covered the whole leaf and subsequently caused defoliation and dieback and whole flowers were blighted. Nine strains of Colletotrichum species were isolated from diseased leaves and flowers and partial ITS rDNA sequences were analysed and morphologies compared across similar species. Based on ITS sequence analysis and morphological characters, three strains were identified as C. truncatum, while one strain was identified as C. siamense. The remaining five strains did not cluster with any known species for which type sequences are available and therefore partial actin (ACT), β-tubulin (TUB2), calmodulin (CAL), glutamine synthetase (GS), glyceraldehyde-3-phosphate dehydrogenase (GPDH) genes of the isolates were sequenced. Based on the reconstructed multiloci molecular phylogeny, two taxa are formally introduced as new species. Another strain was not well resolved in the phylogenetic tree and herein described as Colletotrichum sp. Further studies are needed to prove its distinctiveness. The morphology and growth rate of all taxa are described and compared with similar species.