Analysis of Molecular Diversity in Castanopsis sieboldii with Felt Disease Caused by Septobasidium sp.

Abstract

In 2020, within the Dongbaekdongsan area in Jeju Island, a Septobasidium sp. associated with a felt disease in <i>Castanopsis sieboldii</i> (Makino) Hatus. ex T. Yamaz. & Mashiba was identified. The symptom included the presence of brown, thin, and silk-like mycelial mats attached to the tree's bark, displaying variations in size from large to small. To induce hyphal growth, the samples collected were incubated in a moist chamber, and the newly formed hyphae were subjected to genomic DNA extractions. The nucleotide sequences of the internal transcribed spacer and small subunit rDNA genes were determined, and molecular characteristics among the isolates were investigated through polymerase chain reaction-based restriction fragment length polymorphism analysis. This <i>Septobasidium</i> sp. exhibited distinct morphological and phylogenetic features compared to those that were previously reported in South Korea. Consequently, this strain is taxonomically classified as a provisionally novel species of <i>Septobasidium</i>. Furthermore, the observed felt disease exhibited a high degree of host specificity, as it was exclusively identified in <i>C. sieboldii</i> without occurrence in other tree species at the time of observation.