Peltaster fructicola: Undescribed Sooty Blotch and Flyspeck Species on Apple Fruit in Korea

While investigation of the fungal diseases on apples collected from Cheongsong-gun andBonghwa-gun in Gyeongbuk province, Korea, between August and September 2023 isolatedfive fungal strains from fruits with sooty blotch and flyspeck (SBFS) disease. The strains weredesignated as KNUF-23-CS02, KNUF-23-CS-06, KNUF-23-CS12, KNUF-23-BH01, and KNUF-23-BH03. When grown on potato dextrose agar and 2% water agar, the cultural characteristicsof the strains were similar to those previously reported characteristics of Peltaster fructicolaPf001. The strains produced monoblastic, hyaline conidiogenous cells; the conidia werehyaline, unicellular, cylindrical to ovoidal, and 3.5-7×1.7-3.9 and 4.0-6.6×1.8-3.2 μm in sizeon synthetic nutrient-poor agar or water agars, respectively. Secondary conidia productionby microcyclic conidiation and budding was observed. The KNUF-23-BH03 strain was shownto cause SBFS symptoms similar to those observed on the apples in the pathogenicitytest. Molecular phylogenetic analyses were conducted based on the isolated speciessequences of the internal transcribed spacer region, nuclear large ribosomal DNA subunit,and mitochondrial small ribosomal RNA subunit gene. The five strains were clustered withPeltaster fructicola Pf001. Based on the cultural and morphological characteristics andphylogenetic analysis, the five strains were identified as Peltaster fructicola, which has notbeen previously reported in Korea. KCI Citation Count: 0