A New Colletotrichum Species Associated with Brown Blight Disease on Camellia sinensis

Brown blight, as the most damaging and common foliar disease of the tea plant (Camellia sinensis) in China, has been recently reported to be caused by different species of the genus Colletotrichum. During the years 2016 to 2017, tea plants in commercial tea cultivation areas of Chongqing City that reported significant incidences of brown blight disease were investigated and then analyzed using both morphological characteristics and multilocus phylogenetic analysis. The results showed that at least five species of Colletotrichum were identified, including four well-known species (Colletotrichum gloeosporioides, C. camelliae, C. fioriniae, and C. karstii) and one novel species (C. chongqingense), indicating that there is remarkable species diversity in Colletotrichum spp. present as pathogens. Results of pathogenicity analyses confirmed that C. chongqingense was the causal agent of brown blight and different isolates differed in virulence. C. chongqingense, as a novel pathogen, has never been reported as being associated with brown blight disease in tea plants or anthracnose in other host plants anywhere in the world. Knowledge of the Colletotrichum populations will facilitate further studies addressing the relationships between Colletotrichum spp. and their host plant Camellia sinensis.