Diversity of -Like Species Causing Gray Blight Disease of Tea Plants () in China, Including two Novel Species, and Analysis of Their Pathogenicity.

Several -like species cause gray blight disease in tea plants, resulting in severe tea production losses. However, systematic and comprehensive research on the diversity, geographical distribution, and pathogenicity of pathogenic species associated with tea plants in China is limited. In this study, 168 -like isolates were obtained from diseased tea plant leaves from 13 primary tea-producing provinces and cities in China. Based on a multilocus (internal transcribed spacer, translation elongation factor 1-α, and β-tubulin gene region) phylogenetic analysis coupled with an assessment of conidial characteristics, 20 unclassified isolates, seven species, including two novel ( and ), four known (, , , and ) and one indistinguishable species, and three species, including two known ( and ) and one indistinguishable species, were identified. This study is the first to evaluate on tea plants in China. The geographical distribution and pathogenicity tests showed to be the dominant cause of gray blight of tea plants in China. In vitro antifungal assays demonstrated that theobromine not only derepressed mycelial growth of the 29 representative isolates but also increased their growth. Correlation analysis revealed a linear positive relationship between the mycelial growth rate and pathogenicity ( = 0.0148).