Complete chloroplast genomes of all six Hosta species occurring in Korea: molecular structures, comparative, and phylogenetic analyses

Abstract

BackgroundThe genus Hosta is a group of economically appreciated perennial herbs consisting of approximately 25 species that is endemic to eastern Asia. Due to considerable morphological variability, the genus has been well recognized as a group with taxonomic problems. Chloroplast is a cytoplasmic organelle with its own genome, which is the most commonly used for phylogenetic and genetic diversity analyses for land plants. To understand the genomic architecture of Hosta chloroplasts and examine the level of nucleotide and size variation, we newly sequenced four (H. clausa, H. jonesii, H. minor, and H. venusta) and analyzed six Hosta species (including the four, H. capitata and H. yingeri) distributed throughout South Korea.ResultsThe average size of complete chloroplast genomes for the Hosta taxa was 156,642 bp with a maximum size difference of ~ 300 bp. The overall gene content and organization across the six Hosta were nearly identical with a few exceptions. There was a single tRNA gene deletion in H. jonesii and four genes were pseudogenized in three taxa (H. capitata, H. minor, and H. jonesii). We did not find major structural variation, but there were a minor expansion and contractions in IR region for three species (H. capitata, H. minor, and H. venusta). Sequence variations were higher in non-coding regions than in coding regions. Four genic and intergenic regions including two coding genes (psbA and ndhD) exhibited the largest sequence divergence showing potential as phylogenetic markers. We found compositional codon usage bias toward A/T at the third position. The Hosta plastomes had a comparable number of dispersed and tandem repeats (simple sequence repeats) to the ones identified in other angiosperm taxa. The phylogeny of 20 Agavoideae (Asparagaceae) taxa including the six Hosta species inferred from complete plastome data showed well resolved monophyletic clades for closely related taxa with high node supports.ConclusionsOur study provides detailed information on the chloroplast genome of the Hosta taxa. We identified nucleotide diversity hotspots and characterized types of repeats, which can be used for developing molecular markers applicable in various research area.

Insights into Phylogenetic Relationships and Genome Evolution of Subfamily Commelinoideae (Commelinaceae Mirb.) Inferred from Complete Chloroplast Genomes

“…2). This result has also been identi ed in the other monocots [40][41][42]. It may possibly be attributed to copy correction of the IR regions via gene conversion [43].…”

Comparative Chloroplast Genome Analysis of Impatiens Species (Balsaminaceae) in the Karst Area of China: Insights Into Genome Evolution and Phylogenomic Implications.

“…The nuclear, chloroplast(cp), and mitochondria genomes are the three major organelles that contain their genomes [ 1 ]. Typically, cp genomes in angiosperms comprise a quadripartite circular double-helix structure of highly conserved sizes, structures, and gene sequences ranging from 115 kb to 165 kb [ 2 ]. The common feature of the complete chloroplast genome is a typical tetrad structure, which consists of a pair of inverted repeats(IRs), which are divided by large and small single copy(LSC, SSC).…”

The First Glimpse of Streptocarpus ionanthus (Gesneriaceae) Phylogenomics: Analysis of Five Subspecies’ Chloroplast Genomes

“…Saintpaulia [21]. However, much lower size ranges have been reported in the Hosta (<85 bp) [22] and Pyrus hopeiensis (46 bp) [23] species and, thus, Str. ionanthus cp genomes can be termed as relatively variable.…”