Unveiling two new species of Trichoderma (Hypocreales, Hypocreaceae) that cause green mold disease on Stropharia rugosoannulata from Guizhou Province, China

Abstract

Stropharia rugosoannulata is an important edible mushroom in China, but green mold disease has caused significant production and economic losses. In this study, two new pathogens Trichoderma strophariensis and T. viridistromatis were identified as the causal agents of this disease. During October-November 2023, six strains of the fungal pathogen were isolated from infected fruiting bodies of S. rugosoannulata and identified based on morphological characteristics and molecular phylogenetic analyses of internal transcribed spacer (nrITS), the second largest RNA polymerase II subunit (rpb2) and the partial translation elongation factor 1-alpha (tef1-α) region. The representative isolates of the pathogenic green mold Trichoderma species were used to perform a pathogenicity test with spore suspensions, resulting in symptoms similar to those observed in the cultivated field. The same pathogens were successfully re-isolated, thereby fulfilling Koch’s postulates. Detailed morphological descriptions, illustrations, culture characteristics, and comparisons with morphologically similar and closely related species are provided.