Four Unrecorded Species of Trichoderma (Hypocreales, Ascomycota) from Forest Soils in Korea Based on Morphological and Phylogenetic Analyses

Trichoderma is a diverse genus in the family Hypocreaceae (Hypocreales) with significant ecological roles in forest ecosystem. They contribute to nutrient cycling through decomposition of organic matter and enhance plant growth. Owing to this importance, the morphological, molecular, and enzymatic characteristics of Trichoderma species have been extensively studied worldwide. Approximately, 495 species have been reported worldwide, whereas only 50 species have been recorded in Korea. To narrow this gap, 11 Trichoderma strains were isolated from soil samples collected from fir and deciduous forests in 2013 and 2017. Morphological observations and multi-marker phylogenetic analyses were subsequently conducted using the second largest subunit of RNA polymerase II (rpb2) and translation elongation factor 1-alpha (tef1) regions. Among the strains, four unrecorded Trichoderma species in Korea were identified: T. chlamydosporum, T. concentricum, T. hirsutum, and T. italicum. This study expands the known diversity of Trichoderma in Korea and provides detailed cultural characteristics and phylogenetic relationships of these four unrecorded species.