Athelia rolfsii에 의한 익모초 흰비단병

초록

In 2024, sclerotium rot was observed on oriental motherwort (Leonurus japonicus) plants grown in farm fields in Chilwon-eup, Haman-gun, and Sancheong-eup, Sancheong-gun, Gyeongsangnam-do, South Korea. Symptoms included the soil-line water-soaking and rotting, and the diseased plants were withered and blighted. White mold grew on the petioles and stems of oriental motherwort and the soil surface, and many small, round, and brown sclerotia were formed. Silky white mycelia (4 to 9 ㎛) grew well on potato dextrose agar medium, and characteristic clamp connections were observed. Over time, many small (1 to 3 ㎜), round, and brown sclerotia were formed. For fungal identification, the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene of the fungus isolated from the oriental motherwort plants was analyzed. In the genetic relationship analysis based on the ITS region, the oriental motherwort isolate was included in the same group as the clade of Athelia rolfsii. In addition, the oriental motherwort isolate produced species-specific PCR products in the diagnostic PCR analysis using species-specific primers. In the pathogenicity test, the oriental motherwort isolate-inoculated plants wilted, and sclerotia were formed on the ground. Still, the plants not inoculated with the fungus did not develop the disease. Koch's postulates were satisfied through re-isolation. The causative fungus was identified as Athelia rolfsii based on the symptoms and morphological characteristics, ITS rRNA gene region sequence analysis, phylogenetic analysis, and pathogenicity test. This study is the first report of sclerotium rot of oriental motherwort caused by A. rolfsii in South Korea and will be helpful in managing and controlling sclerotium rot.

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