Single-copy Region Research Articles

The complete chloroplast genome of Swertia davidii (gentianaceae) and its phylogenetic analysis

To elucidate the genetic information and evolutionary relationships of Swertia, we initiated the sequencing of the complete chloroplast genome of Swertia davidii Franch. 1888, complemented by comparative analyses with closely related species. The chloroplast genome of S. davidii was 153,516 bp in length and exhibited a typical quadripartite structure. It contained two regions with Inverted Repeat lengths of 25,767 bp, located between one Large Single-Copy region (83,617 bp) and one Short Single-Copy region (18,365 bp). The chloroplast genome of S. davidii encoded 132 genes, including 87 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. The overall GC content was 38.15%. Maximum likelihood phylogenetic analysis of Swertia based on 26 available plastomes showed a close relationship between S. davidii and S. kouitchensi. This study will contribute to the genetic preservation of the species and the phylogenetic study of Swertia.

Complete chloroplast genome sequence and phylogenetic analysis of Populus maximowiczii Henry 1913 (Salicaceae Mirb.)

The classification and identification of species in Populus has remained a formidable challenge due to widespread interspecies hybridization. The complete chloroplast genome of Populus maximowiczii was obtained by Illumina high-throughput sequencing technology, with a typical quadripartite structure and 37.0% GC content. The chloroplast genome of P. maximowiczii was 156,892 in length, including a large single-copy region (LSC: 84,988 bp), a small single-copy region (SSC: 16,630 bp), and a pair of inverted repeats (IRs: each 27,637 bp in length). A total of 131 genes were annotated, including 86 protein-coding genes, 37 tRNAs, and 8 rRNAs. The phylogenetic analysis indicated that 43 species belonging to Populus were classified into monophyly, with P. cathayana being the closest relatives to P. maximowiczii. In conclusion, this study provides valuable insights into understanding the phylogeny of Populus.

The complete chloroplast genome of Blechnopsis orientalis (Linnaeus) C. Presl 1753 (Blechnaceae)

Blechnopsis orientalis (Linnaeus) C. Presl (1753) is a fern used both as food and medicine. It is found primarily in southern China and Southeast Asia, thriving in warm, humid shrublands or sparse forest. The total length of the chloroplast genome is 155,211 bp, including a large single-copy region (LSC, 81,877 bp), a small single-copy region (SSC, 21,500 bp), and two inverted repeat regions (IRs, 25,917 bp). The GC content is 41.3%. A total of 131 genes were annotated, including 88 protein-coding genes, eight rRNA genes, and 35 tRNA genes. The phylogenetic analysis using the maximum-likelihood method showed that B. orientalis and Oceaniopteris gibba were closely related. This study provides genomic resources for phylogenetic genetics and resource exploitation of B. orientalis.

Complete plastome sequence of Narcissus pseudonarcissus L., one of the most iconic European plants

Narcissus pseudonarcissus L. is one of the most iconic plants of the European flora. It is a species of great horticultural interest, but also an endangered and protected plant in the wild as a consequence of loss of natural habitats. Complete plastid genome was assembled from next-generation sequencing data obtaining a circular genome of 160,008 bp long assembly. It comprises a pair of inverted repeat regions, a large single-copy region (108,400 bp), and a small single-copy region (16,434 bp). It encodes 131 genes, including 87 protein coding genes, 37 tRNA genes and seven rRNA genes. Phylogeny showed the strict relationship between N. pseudonarcissus and Narcissus poeticus L. The complete plastome will provide a useful genetic resource for future conservation programmes, phylogenetic studies and horticultural applications.

Characteristics and phylogenetic analysis of the complete chloroplast genome of Vernonia volkameriifolia DC. 1836 (Asteraceae)

Vernonia volkameriifolia DC. 1836, is a woody shrub of the subfamily Vernonioideae within the family Asteraceae. The complete chloroplast genome of V. volkameriifolia spans 152,934 bp, comprising four subregions: a large single-copy region (84,035 bp), a small single-copy region (18,543 bp), and a pair of inverted repeats (25,178 bp). Within the chloroplast genome of V. volkameriifolia, 114 unique genes were identified, including 80 unique protein-encoding genes, four ribosomal RNA (rRNA) genes, and 30 transfer RNA (tRNA) genes. Phylogenetic analysis based on the complete chloroplast genome of six related taxa in the Vernonieae tribe indicates that V. volkameriifolia show closer relationships with Vernonia parishii and Strobocalyx arborea. The first chloroplast genome of V. volkameriifolia was reported in this work, contributing to the enrichment of genomic data for the genus Vernonia.

The complete chloroplast genome sequence of Hypecoum erectum L. (Papaveraceae)

Hypecoum erectum L., a widespread species in northern Eurasia, is a valuable medicinal plant, but its chloroplast genome has not previously been reported. We determined its complete chloroplast genome using a high-throughput sequencing technique. Its total length was 169,241 bp, consisting of a large single-copy region of 93,301 bp and a small single-copy region of 17,316 bp, separated by a pair of inverted repeat regions of 29,312 bp. A total of 140 genes were annotated, including 91 protein coding genes, 41 tRNA genes, and eight rRNA genes. The phylogenetic analysis shows that H. erectum and H. zhukanum of the subfamily Hypecoideae are monophyletic with the highest support.

Complete chloroplast genome of Asarum chungbuensis (C.S. Yook & J.G. Kim) B.U. Oh 2005 (Aristolochiaceae), a Korean endemic species

Asarum chungbuensis, a species endemic to Korea, has a limited distribution across the Korean Peninsula and is used in traditional medicine. Despite its importance, the genome structure, genetic composition, and phylogenetic relationships based on its chloroplast genome have not been documented. In this study, the complete chloroplast genome of A. chungbuensis was newly assembled. The chloroplast genome is 190,179 base pairs (bp) long, and the overall GC content (%) of the plastid was 36.8%. The chloroplast genome size of A. chungbuensis is longer than that of the normal chloroplast genome (160 kb) because of an inverted small single-copy (SSC) duplication that incorporates the SSC into an inverted repeat (IR) region. By extension, this duplication event causes this chloroplast genome to lack an SSC, unlike other formal structures. The chloroplast genome, with a tripartite structure, consisted of a single-copy region of 93,351 bp with a 34.6% GC content and two IR regions, each with a length of 48,414 bp and a 38.8% GC content. Additionally, it was found to have 113 genes, including 79 PCG genes, 30 tRNA genes, and four rRNA genes. Phylogenetic analysis revealed that A. chungbuensis was grouped with A. heterotropoides var. seoulense, which diverged from the clade comprising A. koreanum and A. patens. The newly sequenced A. chungbuensis chloroplast genome could provide valuable genomic information for determining unique genome structures, especially for the assessment of genetic diversity, phylogenetic relationships, species conservation, and biogeographic studies of the genus Asarum.

Deciphering the complete chloroplast genome sequence of Meconopsis torquata Prain: Insights into genome structure, comparative analysis and phylogenetic relationship

In the present study, we have characterized the complete chloroplast (Cp) genome of Meconopsis torquata Prain (family Papaveraceae), revealing the plastome size of 153,290 bp, and a GC content of 38.72 %. The cp genome features the typical circular quadripartite structure found in flowering plants, including a pair of inverted repeat regions (25,816 bp), isolated by a small single-copy region (17,740 bp) and a large single-copy (83,918 bp). Genome annotation revealed 132 genes: 87 protein-coding genes, 37 tRNAs and eight rRNAs. This comparative study demonstrated that the genome structure, gene number and GC ratio are consistent with several other cp genomes of Meconopsis and Papaver genera. A total of 120 SSRs were detected in the plastome, the majority (111) of which were mononucleotide repeats. Among the longer repeats, palindromic sequences were most common, followed by forward, reverse, and complement repeats. The whole genome alignment revealed the conserved nature of the inverted repeat region over single-copy zones. Nucleotide diversity unveiled hypervariable sites (ycf1, rps16, accD, atpB and psbD) in both the small and large single-copy regions, which could be useful for designing molecular markers for taxonomic identification. Phylogenetic analysis revealed a close alliance of M. torquata with other Meconopsis species, such as M. pinnatifolia and M. paniculata, with strong bootstrap support. Molecular dating suggests that M. torquata originated during the Tortonian age of the Miocene epoch of the Cenozoic era. These findings provide valuable insights for biological research, especially in understanding the genetic and evolutionary divergence within the Papaveraceae family.

Comparative structure and evolution of the organellar genomes of Padina usoehtunii (Dictyotales) with the brown algal crown radiation clade

BackgroundOrganellar genomes have become increasingly essential for studying genetic diversity, phylogenetics, and evolutionary histories of seaweeds. The order Dictyotales (Dictyotophycidae), a highly diverse lineage within the Phaeophyceae, is long-term characterized by a scarcity of organellar genome datasets compared to orders of the brown algal crown radiation (Fucophycidae).ResultsWe sequenced the organellar genomes of Padina usoehtunii, a representative of the order Dictyotales, to investigate the structural and evolutionary differences by comparing to five other major brown algal orders. Our results confirmed previously reported findings that the rate of structural rearrangements in chloroplast genomes is higher than that in mitochondria, whereas mitochondrial sequences exhibited a higher substitution rate compared to chloroplasts. Such evolutionary patterns contrast with land plants and green algae. The expansion and contraction of the inverted repeat (IR) region in the chloroplast correlated with the changes in the number of boundary genes. Specifically, the size of the IR region influenced the position of the boundary gene rpl21, with complete rpl21 genes found within the IR region in Dictyotales, Sphacelariales and Ectocarpales, while the rpl21 genes in Desmarestiales, Fucales, and Laminariales span both the IR and short single copy (SSC) regions. The absence of the rbcR gene in the Dictyotales may indicate an endosymbiotic transfer from the chloroplast to the nuclear genome. Inversion of the SSC region occurred at least twice in brown algae. Once in a lineage only represented by the Ectocarpales in the present study and once in a lineage only represented by the Fucales. Photosystem genes in the chloroplasts experienced the strongest signature of purifying selection, while ribosomal protein genes in both chloroplasts and mitochondria underwent a potential weak purifying selection.ConclusionsVariations in chloroplast genome structure among different brown algal orders are evolutionarily linked to their phylogenetic positions in the Phaeophyceae tree. Chloroplast genomes harbor more structural rearrangements than the mitochondria, despite mitochondrial genes exhibiting faster mutation rates. The position and the change in the number of boundary genes likely shaped the IR regions in the chloroplast, and the produced structural variability is important mechanistically to create gene diversity in brown algal chloroplast.

The complete chloroplast genome sequence of Lemna turionifera (Araceae)

Lemna turionifera is native to North America and northern Asia, with significant potential for industrial wastewater remediation. The complete nucleotide sequence of the L. turionifera chloroplast genome (cpDNA) was determined. The cpDNA is a circular molecule of 166,606 bp and containing a pair of inverted repeats (IRs) measuting 31,663 bp each. These IRs are flanked by a small single-copy region of 13,542 bp and a large single-copy region of 89,738 bp. The chloroplast genome of L. turionifera consisted of 112 unique genes, including 78 protein-encoding genes, 30 tRNA genes, and four rRNA genes. The phylogenetic analysis utilizing cpDNA provided a well-supported resolution of the relationships among subfamilies within the Araceae family. Our findings indicated a close relationship between L. turionifera and a clade consisting of L. minor, L. japonica, and L. gibba. The availability of the complete chloroplast genome sequence of L. turionifera presents valuable data for future phylogenetic investigations within the Lemnaceae family.

Plastome Evolution of Asyneuma japonicum: Insights into Structural Variation, Genomic Divergence, and Phylogenetic Tree

Asyneuma japonicum is an ornamental flowering plant in East Asia. The genus Asyneuma is difficult to distinguish taxonomically because of its morphological similarities with the genus Campanula. We constructed the first complete plastome of A. japonicum (NCBI accession number: OR805474) using the Illumina platform. This plastome is a circular ring structure with a length of 185,875 base pairs. It is organized into four parts: a pair of inverted repeats (33,084 bp each) as well as large (83,795 bp) and small (35,912 bp) single-copy regions. One hundred nine unique genes were encoded in the assembled plastome. Using structural variations, junction boundaries, rearrangements, divergent hotspots, and phylogenetic analysis, we revealed that A. japonicum was in the closest evolutionary position to Hanabusaya asiatica and it had a large evolutionary divergence from the Campanulaceae family due to gene rearrangements.

Intraspecific Differentiation of Styrax japonicus (Styracaceae) as Revealed by Comparative Chloroplast and Evolutionary Analyses.

Styrax japonicus is a medicinal and ornamental shrub belonging to the Styracaceae family. To explore the diversity and characteristics of the chloroplast genome of S. japonicus, we conducted sequencing and comparison of the chloroplast genomes of four naturally distributed S. japonicus. The results demonstrated that the four chloroplast genomes (157,914-157,962 bp) exhibited a typical quadripartite structure consisting of a large single copy (LSC) region, a small single copy (SSC) region, and a pair of reverse repeats (IRa and IRb), and the structure was highly conserved. DNA polymorphism analysis revealed that three coding genes (infA, psbK, and rpl33) and five intergene regions (petA-psbJ, trnC-petN, trnD-trnY, trnE-trnT, and trnY-trnE) were identified as mutation hotspots. These genetic fragments have the potential to be utilized as DNA barcodes for future identification purposes. When comparing the boundary genes, a small contraction was observed in the IR region of four S. japonicus. Selection pressure analysis indicated positive selection for ycf1 and ndhD. These findings collectively suggest the adaptive evolution of S. japonicus. The phylogenetic structure revealed conflicting relationships among several S. japonicus, indicating divergent evolutionary paths within this species. Our study concludes by uncovering the genetic traits of the chloroplast genome in the differentiation of S. japonicus variety, offering fresh perspectives on the evolutionary lineage of this species.

Phylogenomic data resolved the deep relationships of Gymnogynoideae (Selaginellaceae).

The unresolved phylogenetic framework within the Selaginellaceae subfamily Gymnogynoideae (ca. 130 species) has hindered our comprehension of the diversification and evolution of Selaginellaceae, one of the most important lineages in land plant evolution. Here, based on plastid and nuclear data extracted from genomic sequencing of more than 90% species of all genera except two in Gymnogynoideae, a phylogenomic study focusing on the contentious relationships among the genera in Gymnogynoideae was conducted. Our major results included the following: (1) Only single-copy region (named NR) and only one ribosomal operon was firstly found in Afroselaginella among vascular plants, the plastome structure of Gymnogynoideae is diverse among the six genera, and the direct repeats (DR) type is inferred as the ancestral state in the subfamily; (2) The first strong evidence was found to support Afroselaginella as a sister to Megaloselaginella. Alternative placements of Ericetorum and Gymnogynum were detected, and their relationships were investigated by analyzing the variation of phylogenetic signals; and (3) The most likely genus-level relationships in Gymnogynoideae might be: ((Bryodesma, Lepidoselaginella), (((Megaloselaginella, Afroselaginella), Ericetorum), Gymnogynum)), which was supported by maximum likelihood phylogeny based on plastid datasets, maximum likelihood, and Bayesian inference based on SCG dataset and concatenated nuclear and plastid datasets and the highest proportion of phylogenetic signals of plastid genes.

Chloroplast Genome Profiling and Phylogenetic Insights of the “Qixiadaxiangshui” Pear (Pyrus bretschneideri Rehd.1)

The “Qixiadaxiangshui” pear (Pyrus bretschneideri Rehd.1) is a highly valued cultivar known for its crisp texture, abundant juice, and rich aroma. In this study, we reported the first complete chloroplast genome sequence of the “Qixiadaxiangshui” pear, which is 159,885 bp in length with a GC content of 36.58%. The genome exhibits a typical circular quadripartite structure, comprising a large single-copy region (LSC), a small single-copy region (SSC), and a pair of inverted repeat regions (IRs). A total of 131 genes were identified, including 84 protein-coding genes, 8 rRNA genes, and 37 tRNA genes. We also identified 209 simple sequence repeats (SSRs) and several mutation hotspots, such as ndhC-trnM-CAU and trnR-UCU-atpA, which can be applied in molecular identification and phylogenetic studies of Pyrus. Comparative genomic analysis showed high conservation among ten pear cultivars. Phylogenetic analysis indicated that the “Qixiadaxiangshui” pear is closely related to germplasm Dangshansuli, Wonwhang, and Yali, suggesting a recent common ancestor. These findings provided valuable insights into the genetic diversity and evolutionary dynamics of the Pyrus species and contribute to the conservation and breeding of pear germplasm resources.

Complete Chloroplast Genome of Megacarpaea megalocarpa and Comparative Analysis with Related Species from Brassicaceae.

Megacarpaea megalocarpa, a perennial herbaceous species belonging to the Brassicaceae family, has potential medicinal value. We isolated and characterized the chloroplast (cp) genome of M. megalocarpa and compared it with closely related species. The chloroplast genome displayed a typical quadripartite structure, spanning 154,877 bp, with an overall guanine-cytosine (GC) content of 36.20%. Additionally, this genome contained 129 genes, 105 simple sequence repeats (SSRs), and 48 long repeat sequences. Significantly, the ycf1 gene exhibited a high degree of polymorphism at the small single copy (SSC) region and the inverted repeat a (IRa) boundary. Despite this polymorphism, relative synonymous codon usage (RSCU) values were found to be similar across species, and no large segment rearrangements or inversions were detected. The large single copy (LSC) and SSC regions showed higher sequence variations and nucleotide polymorphisms compared to the IR region. Thirteen distinct hotspot regions were identified as potential molecular markers. Our selection pressure analysis revealed that the protein-coding gene rpl20 is subjected to different selection pressures in various species. Phylogenetic analysis positioned M. megalocarpa within the expanded lineage II of the Brassicaceae family. The estimated divergence time suggests that M. megalocarpa diverged approximately 4.97 million years ago. In summary, this study provides crucial baseline information for the molecular identification, phylogenetic relationships, conservation efforts, and utilization of wild resources in Megacarpaea.

Ceratopteris baguangensis (Pteridaceae), a new species of Ceratopteris from Guangdong, China

A new species of fern, Ceratopteris baguangensis was recently discovered in Shenzhen, Guangdong, China. Detailed morphological descriptions and photographs of the habitat are shown. C. baguangensis is similar to C. thalictroides and C. oblongiloba in the morphology of the fertile fronds but is distinct from them in the lobes of the sterile fronds. Furthermore, the chloroplast genome of C. baguangensis was sequenced and characterized. The annotated results revealed that the chloroplast genome had a conserved quadripartite structure, with a pair of inverted repeat regions (IRs) separating the large single copy (LSC) region and the small single copy (SSC) region, resulting in a total length of 149,755 base pairs (bp). The genome encodes a total of 120 unique genes, including 76 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Molecular evidence indicated that the C. baguangensis formed a distinct lineage and was sister to C. oblongiloba. Given the current population size of C. baguangensis in Baguang Heritiera littoralia Wetland Park, it is suggested C. baguangensis should be categorized as an Endangered (EN) species according to the criteria of IUCN. This study further enriches the diversity of the genus Ceratopteris and will help to elucidate their phylogenetic relationships.

The complete chloroplast genome of Leonurus sibiricus Linnaeus (Labiatae, Leonurus Miller)

Leonurus sibiricus Linnaeus 1753, an annual or biennial herb found in northern China, Mongolia, and Russia, typically grows in stony, sandy grasslands, and pine forests. This study sequenced and reported the complete chloroplast genome of L. sibiricus for the first time. The entire circular genome measures 151,689 bp in length, with a GC content of 38.4%. A total of 133 genes were annotated, including 88 protein-coding genes, 37 tRNAs, and eight rRNAs. The genome exhibits a typical quadripartite structure, comprising a large single-copy (LSC 82,820 bp) region, a small single-copy (SSC 17,619 bp) region, and a pair of inverted repeat (IR 25,625 bp each) regions. Phylogenetic analysis using the maximum-likelihood method indicates that L. sibiricus is most closely related to L. japonicus Houttuyn. This study provides valuable genomic resources for further research on the phylogenetics and biodiversity of the genus Leonurus.

The complete chloroplast genome of Polyspora axillaris (Theaceae)

Polyspora axillaris (Roxb. ex Ker Gawl.) Sweet 1825, is a shrub or tree that is about 9 meters tall in the Theaceae family, mainly distributed in China and Vietnam, and it is widely used as a green tree species in many regions owing to its rapid growth and good adaptability. It is rich in various beneficial extracts for humans, but there are limited studies on it. In this study, we sequenced and annotated the complete plastome of P. axillaris. The chloroplast genome length of P. axillaris is 156,770 bp, with a total of 132 genes, including 37 tRNA genes, 8 rRNA genes and 87 protein-coding genes. The complete chloroplast genome of P. axillaris contains two Inverted Repeats (IRs) of 26,077 bp, a Large Single-Copy (LSC) region of 86,286 bp and a Small Single-Copy (SSC) region of 18,330 bp. The overall G/C content in the chloroplast is 37.3%. Phylogenetic inference shows that P. axillaris formed a sister relationship with P. hainanensis, along with 10 Theaceae species. The research result of P. axillaris will contribute to the genetic preservation of the species and the phylogenetic study of Polyspora.

Complete chloroplast genome and phylogenetic analysis of Amorphophallus paeoniifolius (Araceae)

Amorphophallus paeoniifolius (Dennst.) Nicolson, 1885, often known as elephant foot yam, is a tropical tuber crop that originates from south-east Asia and belongs to the Araceae family. It is known for its high production potential and popularity as a medicinal plant. However, the phylogeny and genes for this species are still unavailable. In this study, the first complete chloroplast genome of A. paeoniifolius was reported and phylogenetic analysis was conducted with Araceae species. The chloroplast genome was 176,258 bp in length with 34.80% overall GC content and includes a large single-copy (LSC) region (93,951 bp), a small single-copy (SSC) region (15,013 bp), and a pair of inverted repeat (IRs) regions (33,647 bp). The chloroplast genome has 130 genes, which include 85 protein-coding genes, 37 tRNA genes, and eight rRNA genes. A maximum-likelihood (ML) phylogenetic analysis indicated that all Amorphophallus species formed a single monophyletic clade with a high bootstrap value and A. paeoniifolius was closely related to A. konjac, A. albus, A. krausei, and A. titanum. The chloroplast genome reported in this study will be useful for further taxonomic and evolutionary studies of Amorphophallus.

The first complete chloroplast genome of Cyclamen persicum and its phylogenetic position within Primulaceae

Cyclamen persicum Mill., 1768, is a perennial herb of Primulaceae and is native to the Mediterranean region. In this study, we sequenced the chloroplast genome of Cyclamen persicum. Its complete chloroplast contained 151,911 nucleotides, including a large single-copy (LSC) region with a length of 83,191 bp, a small single-copy (SSC) region with a length of 17,922 bp, and a pair of reverse repeat IR regions (25,399 bp). The C. persicum chloroplast genome encoded 112 unique genes, including 78 protein-coding genes, 30 tRNA genes, and four rRNA genes. The GC content of the entire genome was 37.25%, lower than that of many angiosperm plastome. The phylogenetic result indicated that C. persicum exhibited the closest relationship with Cyclamen rohlfsianum, and provided new information for the phylogeny relationship of genus Cyclamen.