Exploration of Mycobiota in Cypripedium japonicum, an Endangered Species

Orchids live with mycorrhizal fungi in mutualism. This symbiotic relationship plays an essential role in the overall life cycle of orchids from germination, growth, settlement, and reproduction. Among the 1000 species of the orchid, the Korean lady’s slipper, Cypripedium japonicum, is known as an endangered species. Currently, only five natural habitats of the Korean lady’s slipper remain in South Korea, and the population of Korean lady’s slipper in their natural habitat is not increasing. To prevent extinction, this study was designed to understand the fungal community interacting in the rhizosphere of the Korean lady’s slipper living in the native and artificial habitats. In-depth analyses were performed to discover the vital mycorrhizal fungi contributing to habitat expansion and cultivation of the endangered orchid species. Our results suggested that Lycoperdon nigrescens contributed most to the increase in natural habitats and Russula violeipes as a characteristic of successful cultivation. And the fungi that helped L. nigrescens and R. violeipes to fit into the rhizosphere community in Korean lady’s slipper native place were Paraboeremia selaginellae and Metarhizium anisopliae, respectively. The findings will contribute to restoring and maintaining the endangered orchid population in natural habitats.

First Report of Gray Mold Disease on Endangered Species Cypripedium japonicum

Cypripedium japonicum is known to be the indigenous plant to Korea, Japan, and China. However, C. japonicum represents the most critically endangered plant species in South Korea. The plant is esthetically pleasing due to its flower, which is larger than any other orchidaceous species. Disease symptoms relating to gray mold were observed on C. japonicum in May 2019. The suspected pathogen was successfully isolated from the symptomatic leaf tissue and conducted a pure culture of the fungi. The conidia formed consisted of a colorless or light brown single cell, which was either egg or oval-shaped with a size of 7.1 to 13.4 × 5.2 to 8.6 μm. Molecular phylogenetic relationship analysis was also confirmed that the pathogen concerned belonging to the family of Botrytis cinerea. Therefore, the findings confirmed that the pathogen isolated from C. japonicum was consistent with the unique properties of B. cinerea.

Distribution of Rhizosphere and Endosphere Fungi on the First-Class Endangered Plant Cypripedium japonicum

Endangered native plant habitats and populations are rapidly disappearing because of climate and environmental changes. As a representative, the abundance of the first-class endangered wild plant, Cypripedium japonicum, has been rapidly decreasing in Korea. The purpose of this study was to evaluate the distribution of rhizosphere and endophytic fungi on C. japonicum in its native habitat. A total of 440 rhizosphere and 79 endosphere fungi isolates were isolated and identified on the basis of their molecular characteristics. Sixty-five genera and 119 fungi species were identified in this study. The genus Trichoderma showed the highest abundance among both rhizosphere and endosphere fungi. Mortierella, Hypocrea, and Penicillium spp. were also relatively dominant species on C. japonicum. The community structures of rhizosphere and endosphere fungi were similar, but endosphere fungi showed greater diversity.