YONG TAE KIM’s scientific contributions

The genus Aglaothamnion has been separated from Callithamnion based on several characters, most notably the presence of a single nucleus per cell in Aglaothamnion versus multi-nucleate Callithamnion. Few studies have investigated whether these genera are genetically monophyletic. Several species of Aglaothamnion have been reported from Korea, but no phylogenetic studies have been conducted on them. We collected a specimen resembling the genus Aglaothamnion from the east coast of Korea, which is characterized by alternate branching, long axial cells and uninucleate cells. Phylogenetic analyses using rbcL sequences and two DNA-based species delimitation analyses revealed that this specimen is a new species closely related to A. pseudobyssoides. Morphologically, the new species was distinguished by longer axial cells and shorter determinate branches compared to A. pseudobyssoides. The new specimen did not show any reproductive features. Our new species and A. pseudobyssoides are distantly related to other sequences used in the analysis. Our phylogenetic analyses, using our samples and sequences deposited in Genbank, suggests that the named genera, Callithamnion and Aglaothamnion, are not monophyletic, or that the samples were incorrectly named before being submitted to Genbank. While the taxonomy of these two genera requires further analysis, with more markers and type specimens sequenced, it is clear that our new sample is a distinct genetic species. Therefore, we propose the establishment of a new species of Aglaothamnion from Korea, Aglaothamnion inkyui sp. nov.

The oomycete pathogens Pythium porphyrae, causing red rot disease, and Olpidiopsis spp. causing Olpidiopsis-blight, cause serious economic losses to Pyropia sea farms in Korea. During the washing step for Pyropia processing, these pathogens proliferate rapidly, significantly reducing the quality of the final product. To develop non-acidic treatments for these pathogens, various calcium salts were tested against the infectivity of P. porphyrae and Olpidiopsis pyropiae on Pyropia gametophytes, and calcium propionate was the most effective. When Pyropia blades were immersed in 10 mM calcium propionate for 1 h after inoculation with the oomycete pathogen, infection rate of both oomycete pathogens on day 2 was significantly lower (7.1%) than control (>95%). Brief incubation of Pyropia blades in calcium propionate also reduced the spread of infection. The infected area of Pyropia thallus was reduced to 14.3% of the control in 2 days after treatment with 100 mM calcium propionate for 30 s. In field experiments conducted in actual aquaculture farms, it has been shown that a brief 30 s wash every two weeks with 100 mM calcium propionate can effectively reduce the spread of oomycetes throughout the entire culture period. The above results suggest that calcium propionate can be a useful means for controlling the spread of oomycetes not only during laver processing but also during aquaculture.