Phylogenetic variation of eleven soft corals (Anthozoa, Octocorallia) in Nha Trang bay of Vietnam

Coral reef as well as soft corals (Cnidaria: Octocorallia) play an important role in marine environment. Most soft corals belong to order Alcyonacea with three major genera Sinularia, Lobophytum and Sarcophyton. In Vietnam, the Alcyoniidae is the most diverse with 124 species. Up to date, identification of soft coral to species level mostly based on morphological characters. Molecular approaches on determination of soft corals based on partial or complete 18S, partial 28S or partial 16S of ribosomal sequences have been applied recently. Discovery of a unique protein-coding gene, msh1, which is homolog of the bacterial mismatch repair gene mut-S provides an efficient tool for molecular phylogenetic studies of soft corals. msh1 has been found in all octocoral families, with approximately as twice variation as most other protein-coding regions in the octocoral mitochondrial genome. In addition, mitochondrial gene cytochrome c oxidase subunit 1 (cox1) and intergenic regions (IGRs) had been used in several soft coral phylogenetic studies. The combination of cox1, igr1 and msh1 gene markers obviously were more effective than single one. In this study, we investigated for the first time in Vietnam the genetic diversity of soft corals in Nha Trang bay based on 696bp of msh1 gene and 866bp of irg-cox1 fragments. The result indicated that eleven studied specimens were grouped into four different clades including Sinularia, Sarcophyton, Lobophytum and a mixed with Sarcophyton and Lobophytum genera. Both msh1 and irg-cox1 characterized some specific substitutions in each clade to distinguish them from each other. Initial results of this study should facilitate conservation of the soft corals in Vietnam.