Polygonum cuspidatum Siebold & Zucc. is a well-known and widely used medical plant to treat arthritis, gout and inflammation. In this study, we determined the complete chloroplast genome sequence of P. cuspidatum from Zhejiang Province. The assembled chloroplast (cp) genome was 163,183 bp in length, containing two inverted repeated (IR) regions of 30,859 bp each, a large single copy (LSC) region of 87,905 bp, and a small single copy (SSC) region of 13,560 bp. The genome encodes 131 genes, consisting of 86 protein-coding, 37 tRNA, and eight rRNA genes. The overall GC content of P. cuspidatum is 37.53%, with the highest GC content of 41.27% in the IR region. The 86 protein-coding genes encode 27,597 amino acids in total, most of which use the initiation codon ATG, except the ndhD gene which starts with ACG. The length of the tRNA genes range from 48 bp to 88 bp, with the highest GC content of 62.16% in tRNA-Arg (ACG) and tRNA-Asp (GUC). A total of 66 simple sequence repeats are identified in the cp of P. cuspidatum. Phylogenetic analysis indicated a sister relationship between P. cuspidatum and Fallopia sachalinensis, suggesting a close genetic relationship between the genera of Polygonum and Fallopia. This work provides basic genetic resources for investigating the evolutionary status and population genetics of this important medicinal species.

Background Tetrastigma hemsleyanum is a valuable traditional Chinese medicinal plant widely distributed in the subtropical areas of China. It belongs to the Cayratieae tribe, family Vitaceae, and exhibited significant anti-tumor and anti-inflammatory activities. However, obvious differences were observed on the quality of T. hemsleyanum root from different regions, requiring the discrimination strategy for the geographical origins. Result This study characterized five complete chloroplast (cp) genomes of T. hemsleynum samples from different regions, and conducted a comparative analysis with other representing species from family Vitaceae to reveal the structural variations, informative markers and phylogenetic relationships. The sequenced cp genomes of T. hemsleyanum exhibited a conserved quadripartite structure with full length ranging from 160,124 bp of Jiangxi Province to 160,618 bp of Zhejiang Province. We identified 112 unique genes (80 protein-coding, 28 tRNA and 4 rRNA genes) in the cp genomes of T. hemsleyanum with highly similar gene order, content and structure. The IR contraction/expansion events occurred on the junctions of ycf1, rps19 and rpl2 genes with different degrees, causing the differences of genome sizes in T. hemsleyanum and Vitaceae plants. The number of SSR markers discovered in T. hemsleyanum was 56–57, exhibiting multiple differences among the five geographic groups. Phylogenetic analysis based on conserved cp genome proteins strongly grouped the five T. hemsleyanum species into one clade, showing a sister relationship with T. planicaule. Comparative analysis of the cp genomes from T. hemsleyanum and Vitaceae revealed five highly variable spacers, including 4 intergenic regions and one protein-coding gene (ycf1). Furthermore, five mutational hotspots were observed among T. hemsleyanum cp genomes from different regions, providing data for designing DNA barcodes trnL and trnN. The combination of molecular markers of trnL and trnN clustered the T. hemsleyanum samples from different regions into four groups, thus successfully separating specimens of Sichuan and Zhejiang from other areas. Conclusion Our study obtained the chloroplast genomes of T. hemsleyanum from different regions, and provided a potential molecular tracing tool for determining the geographical origins of T. hemsleyanum, as well as important insights into the molecular identification approach and and phylogeny in Tetrastigma genus and Vitaceae family.

Ramie (Boehmeria nivea L. Gaud) is a traditional fiber crop and important medicinal plant belonging to the family Urticaceae. In this study, we determine the complete chloroplast genome sequence of B. nivea. The assembled chloroplast genome is 156065 bp in length and shares the conserved quadripartite structure as other cp genomes in Boehmeria. The genome contains 131 genes, including 84 protein genes, 8 rRNA genes, 37 tRNA genes and 2 pseudo genes. There are 17 duplicated genes in the IR region. The overall GC content of B. nivea is 36.33%, with the highest GC content of 42.72% in IR region. A total of 67 simple sequence repeats are identified in the cp genome of B. nivea. Phylogenetic analysis demonstrated that B. nivea clustered together with B. tomentosa, further forming a monophyletic group with the species of Debregeasia and Pipturus. This work provides basic genetic resources for developing robust markers and investigating the population genetics diversities for B. nivea.

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Oxalis corymbosa DC. is an important medicinal and edible perennial herb belonging to the woodsorrel family Oxalidaceae. In this study, we report the complete chloroplast (cp) genome sequence of O. corymbosa. The assembled chloroplast genome was 151,351 bp in length, containing two inverted repeated (IR) regions of 24,587 bp each, a large single copy (LSC) region of 85,476 bp, and a small single copy (SSC) region of 16,701 bp. The genome encodes 128 genes, consisting of 82 protein-coding genes, 37 tRNA genes, eight rRNA genes, and one pseudogene (ycf1). The 82 protein-coding genes encode 25,751 amino acids in total, most of which use the initiation codon ATG, except rps19 and psbC genes start with GTG. The lengths of the tRNA genes range from 71 bp to 93 bp, with the highest GC content of 62.16% in tRNA-Arg (ACG). The overall GC content of O. corymbosa is 36.47%, with the highest GC content of 42.64% in IR region. In addition, a total of 74 simple sequence repeats were identified in the cp genome of O. corymbosa. Phylogenetic analysis indicated a sister relationship between O. corymbosa and O. drummondii, suggesting a close genetic relationship between the two Oxalis species. This work provides basic genetic resources for investigating the evolutionary status and population genetics diversities for this medicinal species.