Re-evaluation of Armillaria and Desarmillaria in South Korea based on ITS/tef1 sequences and morphological characteristics

Fungal species in the genera Armillaria and Desarmillaria (Physalacriaceae, Agaricales) are well known for their symbiotic relationships with Gastrodia elata and Polyporus umbellatus, important components of traditional medicine in Asia. In addition, some species in these genera cause Armillaria root disease, which has had a negative economic impact by damaging and destroying urban, horticultural and forest trees. Five species within Armillaria and Desarmillaria have been previously reported in South Korea, based primarily on basidioma morphology: A. cepistipes, A. gallica, A. mellea, A. ostoyae and D. tabescens (reported as A. tabescens). This study re-evaluated 60 specimens of Armillaria and Desarmillaria using morphological features and molecular phylogenetic analyses of the ITS and partial translation elongation factor-1α (tef1) sequences. In addition, spatial distributions of each Armillaria and Desarmillaria species in South Korea were determined from combined data based on basidioma collections and environmental DNA (eDNA). Six species (A. cepestipes, A. gallica, A. mellea, A. nabsnona, A. ostoyae and D. tabescens) and three lineages of A. gallica (A. gallica clade 1–3) were identified in South Korea from both specimens and eDNA. Most of the basidioma specimens used in this study were previously identified as A. mellea; however, in this study, no basidioma specimens were identified as A. mellea, although this species was detected on Jeju Island from eDNA samples. The detection of A. nabsnona was a new report for South Korea. Consistent with previous phylogenetic studies, the tef1 analysis had better resolution than the ITS analysis. These distribution data of Armillaria and Desarmillaria species will contribute to better management of Armillaria root disease as well as cultivation of G. elata and P. umbellatus in South Korea.