Identification of Mycorrhizal Symbiont Detected in Roots of Two <i>Cymbidium</i> Species Native to Korea

Abstract

In Korea, the orchid species Cymbidium goeringii and C. kanran are very important as natural genetic resources and floriculture crops. With respect to nutrient uptake, both species mixotrophic, and can shift to autotrophy with the development of photosynthetic organs. In this study, microscope observation was performed to examine the existing symbiotic fungi and their pelotons in root cortical tissues. Molecular identification was performed to identify orchid mycorrhizal fungi (OMF) and evaluate phylogenetic relationships with other OMF taxa in the database. Essential molecular data encompassing ribosomal internal transcribed spacers (ITS) were amplified from the extracted genomic DNA of root tissues. The hyphae grown into cortical root tissues of two individual cymbidiums were observed and revealed to form typical coiled structures called pelotons. OMF sequences obtained from C. goeringii root tissues were determined to be 673 bp nucleotide sequences (MF101371), while those obtained from C. kanran root tissues were 788 bp nucleotide sequences (MF101372). The resulting ITS rDNA sequence was analyzed using the UPGMA cluster analysis method and a dendrogram was generated. According to the phylogenetic tree, the ITS rDNA sequence from C. goeringii was positioned among other Tulasnella species, and that from C. kanran was grouped with Russula species. Producing elementary, but fundamental, data about the nutritionally helpful symbiotic mycorrhizal fungi is very important to facilitate orchid-fungal microbe interactions and for cultivation and conservation programs for native orchids.