Diversity and pathogenicity of pestalotioid fungi infecting Camellia oleifera in China

Oil tea (Camellia oleifera), as one of the four major woody oilseed crops, possesses considerable economic and medicinal significance. The distinctive geographical and climatic conditions of Sichuan Province provide an ideal environment for the growth of C. oleifera, making it a major hub for the C. oleifera industry. However, in recent years, it has suffered severe fungal disease outbreaks, particularly those caused by Pestalotiopsis and Neopestalotiopsis, which infect a wide range of hosts. From August 2023 to May 2024, a comprehensive survey of 66.67 hectares of Camellia oleifera plantations in Sichuan was conducted to identify fungal pathogens. By integrating morphological characterization and phylogenetic analyses of the internal transcribed spacer (ITS), translation elongation factor 1-α (tef1-α), and beta-tubulin (tub2) genes, three pestalotioid species were identified. Among these, N. folii was identified as a novel pathogenic fungus. Furthermore, two new host records were established for P. trachycarpicola and P. hispanica on C. oleifera. Pathogenicity tests following Koch's postulates confirmed strain virulence and revealed variations in pathogenic effects. This study formally recognizes N. folii as a novel species, enhancing current knowledge of pestalotioid fungi associated with C. oleifera.