• The Korean Journal of Mycology
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• v.47 no.4
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• pp.443-446
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• 2019

In 2017, wilting symptom was observed on seedlings of Anthurium andraeranum in Youngin, Korea. Brownish lesions with water soaking were developed on the stems and roots of the infected plants. The stems and leaves wilted and finally died. One fungal isolate was obtained in pure culture. Morphological features and nucleotide sequences of internal transcribed spacer rDNA and cytochrome oxidase subunit II mt DNA were analyzed. The results of this study indicated that the fungus is identified as Phytopythium vexans. Pathogenicity tests showed the isolate was pathogenic to the seedlings of A. andraeanum. To our knowledge, this is the first report of P. vexans causing stem rot on A. andraeanum in Korea.

• Mycobiology
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• v.47 no.3
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• pp.261-272
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• 2019

Oomycetes are widely distributed in various environments, including desert and polar regions. Depending upon different habits and hosts, they have evolved with both saprophytic and pathogenic nutritional modes. Freshwater ecosystem is one of the most important habitats for members of oomycetes. Most studies on oomycete diversity, however, have been biased mostly towards terrestrial phytopathogenic species, rather than aquatic species, although their roles as saprophytes and parasites are essential for freshwater ecosystems. In this study, we isolated oomycete strains from soil sediment, algae, and decaying plant debris in freshwater streams of Korea. The strains were identified based on cultural and morphological characteristics, as well as molecular phylogenetic analyses of ITS rDNA, cox1, and cox2 mtDNA sequences. As a result, we discovered eight oomycete species previously unknown in Korea, namely Phytopythium chamaehyphon, Phytopythium litorale, Phytopythium vexans, Pythium diclinum, Pythium heterothallicum, Pythium inflatum, Pythium intermedium, and Pythium oopapillum. Diversity and ecology of freshwater oomycetes in Korea are poorly understood. This study could contribute to understand their distribution and ecological function in freshwater ecosystem.