The Complete Chloroplast Genome Sequences of Four Saxifragaceae Species
Jae-seo Shin1, Eui-kwon Chung1, Joung-hoon Lee2, Yong-in Kim3, Young-Dong Kim1
1Department of Life Sciences, Hallym University, Chuncheon, Gangwon-do, 24252 S. Korea; 2Multidisciplinary Genome Institute, Life Science Hall, Hallym University, Chuncheon, Gangwon-do, S Korea 24252; 3International Biological Material Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, S. Korea
Saxifragaceae contain approximately 33 genera (640 spp.), of which more than half are monotypic. Phylogenetic relationships and taxonomy within Saxifragaceae have been challenged for a number of factors such as morphological stasis, convergent evolution, evolutionary radiation and disjunctive distribution. In this study, chloroplast genome analyses of four Korean Saxifragaceae taxa were carried out to explore plastid genome evolution and to elucidate the phylogenetic relationships of these taxa. NGS analysis was performed for four Korean taxa belonging to the genus Astilbe, Astilboides, and Chrysosplenium. The length of the chloroplast genome was found to be 157,231 bp for Astilbe chinensis, 156,752 bp for Astilbe koreana, 157,142 bp for Astilboides tabularis and 153,102 bp for Chrysosplenium aureobracteatum. The length of the chloroplast genome of C. aureobracteatum was shown to be the shortest due to reduction in SSC region. A comparison of the gene composition of the four species indicated that the total number of genes were 112~113, CDS 78~79, tRNA 30, rRNA 4. The accD gene of C. aureobracteatum was identified as a pseudogene, while all other gene composition was the same in the four taxa. Phylogenetic analysis was performed using Bayesian Inference (BI) and Maximum Likelihood (ML) estimation for 11 taxa representing 10 genera in the families of Saxifragales. The results showed that Saxifragaceae were identified as sister group of the clade consisted of Penthoraceae and Crassulaceae. In phylogenetic relationships within Saxifragaceae, Astilbe was weakly allied with Heuchera while Astilboides and Bergenia formed a clade, which appeared as sister group of Chrysosplenium. Extremely short branch lengths observed some clades of Saxifragaceae suggested that there was a significant evolutionary radiation at the time of the emergence of the four lineages (Chrysosplenium, Bergenia/Astilboides, Heuchera, and Astilbe).