Unravelling Colletotrichum species associated with Camellia: employing ApMat and GS loci to resolve species in the C. gloeosporioides complex

We investigated the phylogenetic diversity of 144 <i>Colletotrichum</i> isolates associated with symptomatic and asymptomatic tissues of <i>Camellia sinensis</i> and other <i>Camellia</i> spp. from seven provinces in China (Fujian, Guizhou, Henan, Jiangxi, Sichuan, Yunnan, Zhejiang), and seven isolates obtained from other countries, including Indonesia, UK, and the USA. Based on multi-locus (ACT, ApMat, CAL, GAPDH, GS, ITS, TUB2) phylogenetic analyses and phenotypic characters, 11 species were distinguished, including nine well-characterised species (<i>C. alienum</i>, <i>C. boninense</i>, <i>C. camelliae</i>, <i>C. cliviae</i>, <i>C. fioriniae</i>, <i>C. fructicola</i>, <i>C. gloeosporioides</i>, <i>C. karstii</i>, <i>C. siamense</i>), and two novel species (<i>C. henanense</i> and <i>C. jiangxiense</i>). Of these, <i>C. camelliae</i> proved to be the most dominant and probably host specific taxon occurring on <i>Camellia</i>. An epitype is also designated for the latter species in this study. <i>Colletotrichum jiangxiense</i> is shown to be phylogenetically closely related to the coffee berry pathogen <i>C. kahawae</i> subsp. <i>kahawae</i>. Pathogenicity tests and the pairwise homoplasy index test suggest that <i>C. jiangxiense</i> and <i>C. kahawae</i> subsp. <i>kahawae</i> are two independent species. This study represents the first report of <i>C. alienum</i> and <i>C. cliviae</i> occurring on <i>Camellia sinensis</i>. In addition, our study demonstrated that the combined use of the loci ApMat and GS in a phylogenetic analysis is able to resolve all currently accepted species in the <i>C. gloeosporioides</i> species complex.