Identification and characterization of Cladosporium species associated with tea plants (Camellia sinensis) in China

The tea plant (Camellia sinensis) is widely cultivated worldwide as one of the most popular non-alcoholic beverage crops. Cladosporium, the dominant endophytic genus of leaves, possesses a variety of biotransformation and metabolic abilities to promote the accumulation of secondary metabolites. However, Cladosporium species in tea leaves remain unexplored. In this study, a total of 79 Cladosporium isolates were obtained from the leaves of several tea varieties in China. Multilocus phylogenetic analysis and morphological characteristics revealed six known species, namely, C. angulosum, C. anthropophilum, C. halotolerans, C. perangustum, C. tenuissimum and C. xanthochromaticum, and one novel species named C. camelliae. C. angulosum was the most dominant species, and the other six species were newly recorded in tea plants. Pathogenicity tests showed no obvious symptoms of disease in tea leaves caused by 13 representative strains of these seven Cladosporium species. Subsequently, three frequently used fungicides were tested, including chlorothalonil, pyraclostrobin and thiophanate-methyl. The EC50 values against C. tenuissimum were 19.14, 0.548 and 3.796 mu g/mL, respectively. Based on these EC50 values, the inhibition effects of the three fungicides on six strains from six species (C. angulosum, C. anthropophilum, C. camelliae, C. perangustum, C. tenuissimum and C. xanthochromaticum) were further compared. Pyraclostrobin had the strongest inhibitory effects on the mycelial growth of Cladosporium, followed by thiophanate-methyl, and chlorothalonil showed the weakest inhibitory effect. The results provide a basis for understanding endophytic Cladosporium fungi in tea leaves.