Taxonomic re-evaluation of medicinal wood-decaying fungi: Abundisporus, Fomitopsis, and Ganoderma in Korea

Abstract

Wood-decaying fungi are an important group of diverse taxa within the Kingdom Fungi. Wood-decaying fungi are of significant economic value as many species are edible while others are important in both clinical and traditional medicine. For example, species in the genera Fomitopsis and Ganoderma are well known potent natural medicines. In addition, some wood-decaying fungi are important components of forest ecosystems as nutrient turn-over agents while others are serious pathogens. Traditionally, classification of the Fomitopsis and Ganoderma genera was based on morphological characteristics, which are often highly subjective and ambiguous, making identification to the species level unreliable. F. rosea is commonly found in Korea, but this species shares similar characteristics, such as a purple hymenophore surface, with Abundisporus fuscopurpureus and A. Pubertatis, species that have also been described in Korea. Based on morphological re-examination, ecological information and sequence analysis of the internal transcribed spacer (ITS), this study showed that previous classifications were incorrect and there is only one species, A. pubertatis, in Korea. This study provides a detailed description of A. pubertatis in Korea, as well as a taxonomic key to distinguish wood-decaying fungi with purple hymenophores. Morphological and molecular analysis of Fomitopsis specimens collected during the last thirty years indicated that there are eleven Fomitopsis species present in Korea. Among the eleven previously described Fomitopsis species, only F. pinicola was found in this study. Following recent taxonomic and phylogenetic analysis, the majority of Fomitopsis species were transferred to another genus. The second part of this research program focused on improving identification and updating the global range of species within the genus Ganoderma and toward confirming which Ganoderma species are native to Korea. Due to the high morphological similarity of Ganoderma species, identification has previously relied heavily on barcode sequencing using BLAST searches, which are only reliable if the GenBank submissions are accurately labeled. In this study, 113 specimens collected from 1969 – 2016 from various regions in Korea were examined using morphological features and multigene analysis (ITS, translation elongation factor 1-α, and the second largest subunit of RNA polymerase II). Four Ganoderma species were identified: G. sichuanense, G. applanatum, G. adspersum, and G. gibbosum. Phylogenetic analysis at three loci supported the four species distinctions with high bootstrap support. A survey of ~ 600 Ganoderma sequences available on GenBank revealed that many sequences were either misidentified or ambiguously labeled. Corrected annotations for GenBank Ganoderma sequences and their global distribution patterns are provided in this study.