The complete chloroplast genome sequences of six Hylotelephium species: Comparative genomic analysis and phylogenetic relationships.

To evaluate the phylogenetic relationships between Hylotelephium and Orostachys, and to provide important information for further studies, we analyzed the complete chloroplast genomes of six Hylotelephium species and compared the sequences to those of published chloroplast genomes of congeneric species and species of the closely related genus, Orostachys. The total chloroplast genome length of nineteen species, including the six Hylotelephium species analyzed in this study and the thirteen Hylotelephium and Orostachys species analyzed in previous studies, ranged from 150,369 bp (O. minuta) to 151,739 bp (H. spectabile). Their overall GC contents were almost identical (37.7-37.8%). The chloroplast genomes of the nineteen species contained 113 unique genes comprising 79 protein-coding genes (PCGs), 30 transfer RNA genes (tRNAs), and four ribosomal RNA genes (rRNAs). Among the annotated genes, fourteen genes contained one intron, and two genes contained two introns. The chloroplast genomes of the nineteen Hylotelephium and Orostachys species had identical structures. Additionally, the large single copy (LSC), inverted repeat (IR), and small single copy (SSC) junction regions were conserved in the Hylotelephium and Orostachys species. The nucleotide diversity between the Hylotelephium chloroplast genomes was extremely low in all regions, and only one region showed a high Pi value (>0.03). In all nineteen chloroplast genomes, six regions had a high Pi value (>0.03). The phylogenetic analysis showed that the genus delimitation could not be clearly observed even in this study because Hylotelephium formed a paraphyly with subsect. Orostachys of the genus Orostachys. Additionally, the data supported the taxonomic position of Sedum taqeutii, which was treated as a synonym for H. viridescens in previous studies, as an independent taxon.

The complete chloroplast genome sequence of Orostachys minuta (Crassulaceae).

The chloroplast (cp) genome sequence is determined and analyzed for Orostachys minuta for the first time. The cp genome was 150,369 bp in length, containing a large single-copy (LSC) of 82,795 bp and a small single-copy (SSC) of 16,854 bp, which were separated by a pair of 25,360 bp inverted repeats (IRs). The overall G + C content of the O. minuta cp genome amounted to 37.7%. In total, 113 unique genes were annotated, consisting of 79 protein-coding genes (PCGs), 30 transfer RNAs (tRNAs), and four ribosomal RNAs (rRNAs). Among these genes, 18 contained one or two introns. A maximum-likelihood (ML) phylogenetic analysis based on 33 taxa showed that O. minuta formed a clade with O. japonica. This study will provide a baseline as well as valuable molecular phylogenomic information for various future studies to determine the taxonomic position and phylogenetic relationships of the genus Orostachys.

Population Genomics Study and Implications for the Conservation of Zabelia tyaihyonii Based on Genotyping-By-Sequencing.

Zabelia tyaihyonii (Nakai) Hisauti and H. Hara is a perennial shrub endemic to Republic of Korea that grows naturally in only a very limited region of the dolomite areas of Gangwon-do and Chungcheongbuk-do Provinces in the Republic of Korea. Given its geographical characteristics, it is more vulnerable than more widely distributed species. Despite the need for comprehensive information to support conservation, population genetic information for this species is very scarce. In this study, we analyzed the genetic diversity and population structure of 94 individuals from six populations of Z. tyaihyonii using a genotyping-by-sequencing (GBS) approach to provide important information for proper conservation and management. Our results, based on 3088 single nucleotide polymorphisms (SNPs), showed a mean expected heterozygosity (He) of 0.233, no sign of within-population inbreeding (GIS that was close to or even below zero in all populations), and a high level of genetic differentiation (FST = 0.170). Analysis of molecular variance (AMOVA) indicated that the principal molecular variance existed within populations (84.5%) rather than among populations (17.0%). We suggested that six management units were proposed for conservation considering Bayesian structure analysis and phylogenetic analysis, and given the various current situations faced by Z. tyaihyonii, it is believed that not only the in situ conservation but also the ex situ conservation should be considered.