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Abstract Background Spiraea is a genus of deciduous shrubs that contains 80-120 species, is mainly distributed in the Northern Hemisphere and has diversified in East Asia. Spiraea species are cultivated as ornamental plants and some are used in traditional herbal medicine. Based on morphological characteristics and genetic markers, phylogenetic classification exhibits low discriminatory power. Results In present study, we assembled and characterized the chloroplast (cp) genomes of ten Spiraea species and comparatively analysed with five reported cp genomes of this genus. The cp genomes of the fifteen Spiraea species, ranging from 155,904 to 158,637 bp in length, were very conserved and no structural rearrangements occurred. A total of 85 protein-coding genes (PCGs), 37 tRNAs and 8 rRNAs were annotated. We also examined 1,010 simple sequence repeat (SSR) loci, most of which had A/T base preference. Comparative analysis of cp genome demonstrated that single copy and non-coding regions were more divergent than the inverted repeats (IRs) and coding regions and six mutational hotspots were detected. Selection pressure analysis showed that all PCGs were under purifying selection. Phylogenetic analysis based on the complete cp genome data showed that Spiraea formed a monophyletic group and was further divided into two major clades. Infrageneric classification in each clade was supported with a high resolution value. Moreover, the phylogenetic trees based on each individual mutational hotspot segment and their combined dataset also consisted of two major clades, but most of the phylogenetic relationships of interspecies were not well supported. Conclusions Although the cp genomes of Spiraea species exhibited high conservation in genome structure, gene content and order, a large number of polymorphism sites and several mutation hotspots were identified in whole cp genomes, which might be sufficiently used as molecular markers to distinguish Spiraea species. Phylogenetic analysis based on the complete cp genome indicated that infrageneric classification in two major clades was supported with high resolution values. Therefore, the cp genome data of the genus Spiraea will be effective in resolving the phylogeny in this genus.

Paris stigmatosa is a new described species of Melanthiaceae. In this study, the complete chloroplast (cp) genome sequence of P. stigmatosa was first reported and characterized. The cp genome is 165,623 bp in length and contains a pair of inverted repeats (IRs, 34,165 bp) separated by a large (84,327 bp) and small (12,966 bp) single-copy regions. A total of 113 genes were predicted, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that P. stigmatosa is sister of the clade formed by P. marmorata and P. luquanensis.

Paris delavayi Franchet is a perennial herb of the family Melanthiaceae. In this study, the complete chloroplast (cp) genome sequence of P. delavayi was characterized. The cp genome is 164,195 bp in length and contains a pair of inverted repeats (33,415 bp) separated by a large (84,400 bp) and small (12,965 bp) single-copy regions. A total of 112 unique genes were predicted, including 78 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that P. delavayi is sister to P. mairei but with low support.

The first complete chloroplast (cp) genome sequences of an endemic and endangered species in China, Calanthe henryi, were reported in this study. The cp genome of C. henryi was 158,256 bp long, with two inverted repeat (IR) regions of 26,348 bp, a large single copy (LSC) region of 87,137 bp, and a small single copy (SSC) region of 18,423 bp. The cp genome of this species contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content was 36.7%. Phylogenetic analysis of 60 cp genomes within the subfamily of Epidendroideae suggests that C. henryi is closely related to C. bicolor.

The first complete chloroplast (cp) genome sequences of Pittosporum tobira were reported in this study. The cp genome of P. tobira was 153,754 bp long, which included a large single copy (LSC) region of 85,010 bp and a small single copy (SSC) region of 18,740 bp separated by two inverted repeat (IR) regions of 25,002 bp. The cp genome of this species contained 113 unique genes, including 79 protein-coding genes, 30 transfer RNA genes and 4 ribosomal RNA genes. The overall GC content was 38.3%. Phylogenetic analysis of the complete cp genomes within the order Apiales suggested that P. tobira, the representative of Pittosporaceae, is sister to the families of Apiaceae and Araliaceae.

The complete cp genome of Piuns wangii was 117,014 bp in size, containing a large single copy (LSC, 64,061 bp) region and a small single copy (SSC, 52,007 bp) region separated by two reduced inverted repeats (IRs, 473 bp). A total of 107 genes were predicted, including 73 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Most of the 51 simple sequence repeats (SSRs) were mononucleotides motifs of A/T types and were found to be located in non-coding regions. Phylogenetic analysis of Asian Pinus showed P. wangii clustered a strongly-supported clade with Pinus morrisonicola, Pinus sibirica, Pinus wallichiana, and Pinus pumila.

Achyranthes bidentata (Amarathaceae) has been commonly used as a traditional Chinese medicine in the treatment of osteoporosis and bone nonunion. Here, the complete chloroplast genome of A. bidentata was assembled and characterized. The cp genome is 151,451 bp in length, composed of a pair of 25,150 bp inverted repeat (IR) regions separated by a large single-copy (LSC) region of 83,899 bp and a small single-copy (SSC) region of 17,252 bp. The whole cp genome of A. bidentata contains 130 genes(85 protein-coding genes, 37 tRNAs and eight rRNAs) and the overall GC content is 36.5%. Phylogenetic analysis based on the cp genome data showed that A. bidentata was close to Cyathula capitata.

Acer yangbiense Y.S. Chen & Q.E. Yang is a species of Aceraceae with a very restricted distribution in Yunnan, China. In this study, the complete chloroplast (cp) genome sequence of A. yangbiense was reported and characterized. The cp genome is 155,706 bp in length and contains a pair of inverted repeats (IRs, 25,858 bp) separated by a large (85,859 bp) and small (18,131 bp) single-copy regions. A total of 128 genes were predicted, including 83 protein-coding genes, 37 tRNA genes and 8 rRNA genes. The phylogenetic analysis suggested that A. yangbiense is sister of the clade formed by A. laevigatum, A. palmatum, A. wilsonii, and A. buergerianum.

Engelhardia roxburghiana is a traditional Chinese medicine in the Juglandaceae family. In this study, the complete chloroplast (cp) genome sequence of E. roxburghiana was reported and characterized. The cp genome is 161,550 bp in length and contains a pair of inverted repeats (IRs, 25,862 bp) separated by a large (90,937 bp) and small (18,889 bp) single-copy regions. A total of 113 unique genes were predicted, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that E. roxburghiana is resolved as a sister group to the clade of subfam. Juglandoideae.

Uncaria rhynchophylla is a vine plant belonging to the family Rubiaceae and has been used as medicine for a long time in China. In this study, the complete chloroplast (cp) genome sequence of U. rhynchophylla was first reported and characterized. The cp genome was 154,605 bp in length and contains a pair of inverted repeats (IRs, 34,165 bp each) separated by a large (84,327 bp) and small (12,966 bp) single-copy regions. A total of 113 unique genes were predicted, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that U. rhynchophylla was closer to Neolamarckia cadamba.

The first complete chloroplast genome (cp) sequences of Silene jenisseensis were reported in this study. The S. jenisseensis cp genome was 150,299 bp in size, with two inverted repeat (IR) regions of 25,384 bp, the large single-copy (LSC) region of 82,153 bp, and the small single-copy (SSC) region of 17,378 bp. The cp genome of this species contained 111 genes, including 77 protein-coding genes, 4 ribosomal RNA, and 30 transfer RNA genes. The overall GC content was 36.4%. Phylogenetic analysis of the cp genomes within the Caryophyllaceae family suggests that S. jenisseensis is closer to the clade formed by S. capitata and S. aprica.

The first complete chloroplast (cp) genome of Indofevillea khasiana was reported in this study. The I. khasiana cp genome was 159,238 bp in size, with two inverted repeat (IR) regions of 26,275 bp separated by a large single copy (LSC) region of 88,538 bp and a small single copy (SSC) region of 18,150 bp. The cp genome of this species contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content was 36.9%. Phylogenetic analysis based on the cp genome sequences suggests that I. khasiana is sister to the rest species of subfam. Cucurbitoideae.

The first complete chloroplast (cp) genome of Hovenia dulcis was reported in this study. The H. dulcis cp genome was 161,636 bp long with two inverted repeat (IR) regions of 26,574 bp, the large single-copy (LSC) region of 89,574 bp, and the small single-copy (SSC) region of 18,914 bp. The cp genome of this species contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content was 36.6%. Phylogenetic analysis based on the complete cp genomes within the Rhamnaceae family suggests that H. dulcis is closer to the genus of Ziziphus.

The first complete chloroplast genome (cp) sequences of Gentiana rhodantha were reported in this study. The cp genome of G. rhodantha was 148,967 bp in size, with two inverted repeat (IR) regions of 25,760 bp, the large single copy (LSC) region of 79,831 bp, and the small single copy (SSC) region of 17,616 bp. The cp genome contained 112 genes, including 78 protein-coding genes, 4 ribosomal RNA, and 30 transfer RNA genes. The overall GC content was 36.4%. Phylogenetic analysis of the cp genomes within the tribe Gentianeae suggests that G. rhodantha is in a sister clade of other subtribe Gentianinae.

Humulus yunnanensis is an endemic species in Yunnan, China, which is used for beer and pharmacology industry. The phylogenetic position of this species in Humulus remains controversial. The complete chloroplast (cp) genome sequence of H. yunnanensis was reported and characterized in this study. The cp genome is 153,612 bp in length and contains a pair of inverted repeats (IRs, 29,824 bp) separated by a large (87,728 bp) and small (15,390 bp) single-copy regions. A total of 112 unique genes were predicted, including 78 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. The phylogenetic analysis revealed that H. yunnanensis is more closely related to H. scandens than H. lupulus.

The complete chloroplast (cp) genome of Pinus squamata, a critically endangered species in China, was reported in this study. The cp genome is 118,300 bp in length and has four regions: 65,298 bp of large single copy (LSC) region and 52,098 bp of small single copy (SSC) region separated by 452 bp of highly reduced inverted repeat (IR) regions. This cp genome with GC content of 38.8% contains 107 unique genes (73 protein-coding genes, 30 tRNA genes, and four rRNA genes). Phylogenetic analysis based on the complete cp genomes indicates that P. squamata is closer to P. gerardiana than P. bungeana.

Ruta graveolens L. is a perennial plant belonging to the family Rutaceae and has been used for traditional medicines for a long time. In this study, the complete chloroplast (cp) genome sequence of R. graveolens was first reported and characterized. The cp genome is 157,434 bp in length and contains a pair of inverted repeats (IRs, 26,868 bp) separated by a large (85,387 bp) and small (18,311 bp) single-copy regions. A total of 132 genes were predicted, including 87 protein-coding genes, 37 tRNA genes and 8 rRNA genes. The phylogenetic analysis suggested that R. graveolens is more closely related to the monophyletic subfam. Aurantioideae.

The complete chloroplast (cp) genome of Magnolia wilsonii, an endangered and endemic species in China, was first reported in this study. The M. wilsonii cp genome was 157,434 bp in length, including two inverted repeat (IR) regions of 26,868 bp, a large single copy (LSC) region of 85,387 bp, and a small single copy (SSC) region of 18,311 bp. A total of 113 unique genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes, were annotated. The overall GC content was 38.8%. Phylogenetic analysis of 34 representative cp genomes within the genus Magnolia suggests that M. wilsonii was sister to M. sieboldii.

Paederia scandens has been used as a traditional medicine in Asian countries to treat jaundice, dysentery, and the pain of rheumatism. The complete chloroplast (cp) genome sequence of P. scandens was reported and characterized in this study. The cp genome is 153,626 bp in length, composed of a pair of 26,513 bp inverted repeat (IR) regions separated by a large single-copy (LSC) region of 83,712 bp and a small single-copy (SSC) region of 16,888 bp. There were 131 predicted genes (86 protein-coding genes, 37 tRNA genes, and 8 rRNA genes) in the genome, and the overall GC content of the genome is 37.7%. Phylogenetic analysis based on the cp genome data showed that P. scandens was sister to the clade formed by Galium mollugo and G. aparine.

The complete chloroplast (cp) genome of Rosa berberifolia was assembled from high-throughput Illumina sequencing data. The cp genome of R. berberifolia was 156,886 bp in length with a typical quadripartite circular, containing a pair of inverted repeats (26,047 bp) separated by a large (86,045 bp), and small (18,747 bp) single-copy regions. It contains 129 genes, including 84 protein-coding genes, 8 ribosomal RNA genes, 37 transfer RNA genes, and 1 pseudogene (ycf1). The overall GC content of the whole cp genome was 37.2%. Phylogenetic analysis based on the complete chloroplast genomes suggested that R. berberifolia was sister to R. persica.

The first complete chloroplast (cp) genome of the Chinese endemic and endangered species, Magnolia omeiensis, were reported in this study. The M. omeiensis cp genome was 160,091 bp in length, with two inverted repeat (IR) regions of 26,584 bp, one large single-copy (LSC) region of 88,160 bp, and one small single-copy (SSC) region of 18,763 bp. The cp genome of this species contained 113 unique genes, including 79 protein-coding genes, four ribosomal RNA, and 30 transfer RNA genes. The overall GC content was 39.3%. Phylogenetic analysis of 24 representative cp genomes within the genus Magnolia suggested M. omeiensis is closely related to M. yunnanensis.