Diversity of <i>Pestalotiopsis</i>-Like Species Causing Gray Blight Disease of Tea Plants (<i>Camellia sinensis</i>) in China, Including two Novel <i>Pestalotiopsis</i> Species, and Analysis of Their Pathogenicity

Abstract

Several <i>Pestalotiopsis</i>-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 <i>Pestalotiopsis</i>-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 <i>Neopestalotiopsis</i> unclassified isolates, seven <i>Pestalotiopsis</i> species, including two novel (<i>Pestalotiopsis menhaiensis</i> and <i>Pestalotiopsis sichuanensis</i>), four known (<i>Pestalotiopsis camelliae</i>, <i>Pestalotiopsis chamaeropis</i>, <i>Pestalotiopsis kenyana</i>, and <i>Pestalotiopsis rhodomyrtus</i>) and one indistinguishable species, and three <i>Pseudopestalotiopsis</i> species, including two known (<i>Pseudopestalotiopsis camelliae-sinensis</i> and <i>Pseudopestalotiopsis chinensis</i>) and one indistinguishable species, were identified. This study is the first to evaluate <i>Pestalotiopsis chamaeropis</i> on tea plants in China. The geographical distribution and pathogenicity tests showed <i>Pseudopestalotiopsis camelliae-sinensis</i> 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 (<i>P</i> = 0.0148).