Revisiting Pseudocercospora puerariicola associated with leaf spot on Pueraria montana var. lobata with morphological and molecular-phylogenetic data in Korea

Pseudocercospora puerariicola, a leaf spot fungus of Pueraria species, has been reported in East Asian countries, including Korea. Despite the ecological significance of this fungus, to date, no living cultures are present in Korea. The DNA nucleotide sequences of the internal transcribed spacer (ITS) region and the 28S rDNA gene (large subunit, LSU) of the fungus were deposited on GenBank database from Chinese, Laos, and Taiwanese isolates. However, these results were not sufficient to confirm pathogen identification to the species level. Therefore, we aimed to provide further information on this species based on the Korean isolates obtained from Pueraria montana var. lobata, adding more genetic locus to our study to support and affirm the identification of the fungus based on multi-loci analyses from Korean isolates. Nine samples were collected from different areas of Korea and deposited at the Korea University Herbarium, then used in this study. Three monoconidial isolates were obtained in 2022, and molecular phylogenetic analyses were performed using a combined multi-locus dataset of the ITS region, partial actin (actA), partial translation elongation factor 1-alpha (tef-1), and partial DNA-directed RNA polymerase II second largest subunit (rpb2) genes. The present study confirmed the presence of P. puerariicola in Korea as a causal agent of leaf spots on kudzu plants, providing the phylogenetic position of this fungus for the first time based on a multigene dataset and preserving three isolates in an authentic culture collection for future studies.