Malus floribunda Siebold. (Malus) is widely cultivated all over the world, which is of high ornamental value and breeding significance. Comparative analysis of the chloroplast genome can help enrich the phylogenetic relationship and facilitate germplasm utilization of Malus. Based on the whole genome sequencing data, a complete chloroplast genome (M. floribunda) with tetrad structure was assembled. The chloroplast genome (160 037 bp) was composed of a large single-copy (LSC) region (88 142 bp), inverted repeat (IR) B (26 353 bp), a small single-copy (SSC) region (19 189 bp), and IRA (26 353 bp). A total of 111 genes were annotated: 78 protein-coding genes, 29 tRNA genes and 4 rRNA genes. In addition, a large number of repeat sequences were identified in the genome, which was slightly different from that of M. sieboldii and M. toringoides. As for the relative synonymous codon usage, 30 high-frequency codons were found, and the codons tended to end with A/T. The results of interspecific sequence alignment and boundary analysis suggested the sequence variation of the LSC region was large, and the expansion and contraction of the SC region and IR region of the eight Malus species were generally similar. According to the phylogenetic analysis of chloroplast genome sequences, M. floribunda, M. hupehensis, and M. toringoides were grouped into one clade. The findings in this study can provide data support for the development of genetic markers and utilization of germplasm resources in the future.
Genome, Chloroplast ; Malus ; Phylogeny ; Plant Breeding ; Codon

Docynia longiunguis is a plant uniquely present in China and is of high edible and medicinal value. The analysis of its chloroplast genome will help clarify the phylogenetic relationship among Docynia and facilitate the development and utilization of D. longiunguis resources. Based on the alignment of chloroplast genome sequences of related species, the phylogeny and codon preference were analyzed. The total length of D. longiunguis chloroplast genome sequence was 158 914 bp (GenBank accession number is MW367027), with an average GC content of 36.7%. The length of the large single-copy (LSC), the small single-copy (SSC), and inverted repeats (IRs) are 87 020 bp, 19 156 bp, and 26 369 bp, respectively. A total of 102 functional genes were annotated, including 72 protein-coding genes, 26 tRNA genes, and 4 rRNA genes. The best model for constructing phylogenetic tree was TVM+F+R2. D. longiunguis and Docynia indica were clustered into a single group, while Docynia and Malus were clustered into a single group. Comparison of the chloroplast genome sequences of D. longiunguis and its five related species revealed that trnY (GUA)-psbD, ndhC-trnV (UAC), accD-psaI, psbZ-trnfM (CAU), ndhF-trnL gene regions varied greatly. The nucleic acid diversity analysis showed that there were 11 high variation areas with nucleotide variability > 0.01, all were located in the LSC and SSC regions. Except for D. longiunguis, the trnH genes in other sequences were located at the IRs/LSC junction and did not cross the boundary. Codon preference analysis showed that D. longiunguis chloroplast genome has the largest number of isoleucine (Ile) codons, up to 1 205. D. longiunguis has the closest genetic relationship with Malus baccata, Malus sieboldii, Malus hupehensis and Chaenomeles sinensis. Its chloroplast genome codon prefers to end with A/T. The chloroplast genome of D. longiunguis and other Rosaceae chloroplast genomes showed great differences in gene distribution in four boundary regions, while relatively small differences from the chloroplast genomes of Docynia delavayi and D. indica of the same genus were observed. The genome annotation, phylogenetic analysis and sequence alignment of chloroplast genome of D. longiunguis may facilitate the identification, development and utilization of this species.
Codon Usage ; Genome, Chloroplast ; Genomics ; Phylogeny ; Rosaceae

In order to characterize the chloroplast genome and phylogenetic relationships of Isopyrum anemonoides, we performed Illumina Hiseq high-throughput sequencing to sequence the complete chloroplast genome of this plant and constructed a whole-genome map based on contig assembly and annotation. The chloroplast genome of I. anemonoides is 161 034 bp in length and has a typical tetrad structure, comprising 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. The genome also contains a total of 44 dispersed repeat sequences and 47 simple sequence repeats. Among the genome's 53 678 codons, the largest proportion are leucine-encoding codons (5 251), whereas the smallest proportion encode tryptophan (712). Colinear analysis revealed an absence of inversions and rearrangements between I. anemonoides and related species at the chloroplast genome level. Whereas phylogenetic analysis indicated that I. anemonoides did not cluster in a clade with I. manshuricum, it did show a very close phylogenetic relationship with Paraquilegia microphylla. The findings of this study provide basic data that will contribute to further species identification and phylogenetic study of the genus Isopyrum.
Codon ; Genome, Chloroplast/genetics* ; Microsatellite Repeats ; Phylogeny ; Ranunculaceae/genetics*

To explore the different chloroplast genome characteristics of Sinopodophyllum hexandrum, five chloroplast genome sequences of S. hexandrum were compared. Its genome map, repeat sequence, codon preference, inverted repeat (IR)/single-copy (SC) boundary, alignment of chloroplast genome sequences and phylogenetic were analyzed using bioinformatics tools. The results showed that: the total length of five chloroplast genomes of S. hexandrum, with a typical tetrad structure, were 157 203-157 940 bp, and a total of 133-137 genes were annotated, reflecting the diversity of chloroplast genomes of S. hexandrum. Different chloroplast genomes of S. hexandrum has different simple sequence repeat (SSR), where simple repeat of single nucleotide of A/T were the majority among the SSR detected. The interspersed repetitive sequences included direct, palindromic and inverted repeats. The value of effective number of codon (ENc) which was analyzed by using codon bias was 51.14~51.17, the proportion of GC and GC3s was less than 50%, the codon usage pattern tended towards frequently use of A/U-ending bases. Genome sequences and the IR/SC boundaries of five chloroplast genomes of S. hexandrum were relatively conservative. Phylogenetic analysis showed that S. hexandrum and Podophyllum pettatum had the closest genetic relationship. In summary, the chloroplast genome characteristics and evolutionary relationship of different chloroplast genomes of S. hexandrum were obtained, which may facilitate the utilization, protection, variety identification and genetic evolution of S. hexandrum resources.
Phylogeny ; Genome, Chloroplast ; Chloroplasts/genetics* ; Genomics ; Evolution, Molecular

Reynoutria japonica Houtt., belonging to Polygoneae of Polygonaceae, is a Chinese medicinal herb with the functions of draining dampness and relieving jaundice, clearing heat and detoxifying, dispersing blood stasis and relieving pain, and relieving cough and resolving phlegm. In this study, we carried out high-throughput sequencing for the chloroplast genome sequences of five cultivars of R. japonica and analyzed the genome structure and variations. The chloroplast genomes of the five R. japonica cultivars had two sizes (163 376 bp and 163 371 bp) and a typical circular tetrad structure composed of a large single-copy (LSC) region of 85 784 bp, a small single-copy (SSC) region of 18 616 bp, and a pair of inverted repeat (IR) regions (IRa/IRb) which are spaced apart. A total of 161 genes were obtained by annotation, which consisted of 106 protein-coding genes, 10 rRNA-coding genes, and 45 tRNA-coding genes. The total GC content was 36.7%. Specifically, the GC content in the LSC, SSC, and IR regions were 34.8%, 30.7%, and 42.7%, respectively. Comparison of the whole chloroplast genome among the five cultivars showed that trnk-UUU, rpoC1, petD, rpl16, ndhA, and rpl12 in coding regions had sequence variations. In the phylogenetic tree constructed for the 11 samples of Polygoneae, the five cultivars of R. japonica clustered into one clade near the root and was a sister group of Fallopia multiflora (Thunb.).
Base Composition ; Genome, Chloroplast/genetics* ; Open Reading Frames ; Phylogeny ; Reynoutria

Ligustri Lucidi Fructus, the sun-dried mature fruit of Ligustrum lucidum, is cool, plain, sweet, and bitter, which can be used as both food and medicine, with the effects of improving vision, blacking hair, and tonifying liver and kidney. It takes effect slowly. However, little is known about the genetic information of the medicinal plant and it is still a challenge to distinguish Ligustrum species. In this study, the complete chloroplast genome of L. lucidum was obtained by genome skimming and then compared with that of five other Ligustrum species, which had been reported. This study aims to evaluate the interspecific variation of chloroplast genome within the genus and develop molecular markers for species identification of the genus. The result showed that the chloroplast genome of L. lucidum was 162 162 bp with a circular quadripartite structure of two single-copy regions separated by a pair of inverted repeats. The Ligustrum chloroplast genomes were conserved with small interspecific difference. Comparative analysis of six Ligustrum chloroplast genomes revealed three variable regions(rbcL-accD, ycf1a, and ycf1b), and ycf1a and ycf1b can be used as the species-specific DNA barcode for Ligustrum. Phylogeny analysis provided the best resolution of Ligustrum and supported that L. lucidum was sister to L. gracile. This study clarified the genetic diversity of L. lucidum from provenance, which can serve as a reference for further analysis of pharmacological differences and breeding of excellent varieties with stable drug effects.
Fruit ; Genome, Chloroplast ; Ligustrum/genetics* ; Phylogeny ; Plant Breeding

"Tangjie" leaves of cultivated Qinan agarwood were used to obtain the complete chloroplast genome using high-throughput sequencing technology. Combined with 12 chloroplast genomes of Aquilaria species downloaded from NCBI, bioinformatics method was employed to determine the chloroplast genome characteristics and phylogenetic relationships. The results showed that the chloroplast genome sequence length of cultivated Qinan agarwood "Tangjie" leaves was 174 909 bp with a GC content of 36.7%. A total of 136 genes were annotated, including 90 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Sequence repeat analysis detected 80 simple sequence repeats(SSRs) and 124 long sequence repeats, with most SSRs composed of A and T bases. Codon preference analysis revealed that AUU was the most frequently used codon, and codons with A and U endings were preferred. Comparative analysis of Aquilaria chloroplast genomes showed relative conservation of the IR region boundaries and identified five highly variable regions: trnD-trnY, trnT-trnL, trnF-ndhJ, petA-cemA, and rpl32, which could serve as potential DNA barcodes specific to the Aquilaria genus. Selection pressure analysis indicated positive selection in the rbcL, rps11, and rpl32 genes. Phylogenetic analysis revealed that cultivated Qinan agarwood "Tangjie" and Aquilaria agallocha clustered together(100% support), supporting the Chinese origin of Qinan agarwood from Aquilaria agallocha. The chloroplast genome data obtained in this study provide a foundation for studying the genetic diversity of cultivated Qinan agarwood and molecular identification of the Aquilaria genus.
Phylogeny ; Genome, Chloroplast ; Codon ; Molecular Sequence Annotation ; Thymelaeaceae/genetics*

The structure and size of the chloroplast genome of Castanopsis hystrix was determined by Illumina HiSeq 2500 sequencing platform to understand the difference between C. hystrix and the chloroplast genome of the same genus, and the evolutionary position of C. hystrix in the genus, so as to facilitate species identification, genetic diversity analysis and resource conservation of the genus. Bioinformatics analysis was used to perform sequence assembly, annotation and characteristic analysis. R, Python, MISA, CodonW and MEGA 6 bioinformatics software were used to analyze the genome structure and number, codon bias, sequence repeats, simple sequence repeat (SSR) loci and phylogeny. The genome size of C. hystrix chloroplast was 153 754 bp, showing tetrad structure. A total of 130 genes were identified, including 85 coding genes, 37 tRNA genes and 8 rRNA genes. According to codon bias analysis, the average number of effective codons was 55.5, indicating that the codons were highly random and low in bias. Forty-five repeats and 111 SSR loci were detected by SSR and long repeat fragment analysis. Compared with the related species, chloroplast genome sequences were highly conserved, especially the protein coding sequences. Phylogenetic analysis showed that C. hystrix is closely related to the Hainanese cone. In summary, we obtained the basic information and phylogenetic position of the chloroplast genome of red cone, which will provide a preliminary basis for species identification, genetic diversity of natural populations and functional genomics research of C. hystrix.
Phylogeny ; Genome, Chloroplast ; Codon/genetics* ; Genomics ; Chloroplasts/genetics*

In this study, the chloroplast genome of Camellia insularis Orel & Curry was sequenced using high-throughput sequencing technology. The results showed that the chloroplast genome of C. insularis was 156 882 bp in length with a typical tetrad structure, encoding 132 genes, including 88 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Codon preference analysis revealed that the highest number of codons coded for leucine, with a high A/U preference in the third codon position. Additionally, 67 simple sequence repeats (SSR) loci were identified, with a preference for A and T bases. The inverted repeat (IR) boundary regions of the chloroplast genome of C. insularis were relatively conserved, except for a few variable regions. Phylogenetic analysis indicated that C. insularis was most closely related to C. fascicularis. Yellow camellia is a valuable material for genetic engineering breeding. This study provides fundamental genetic information on chloroplast engineering and offers valuable resources for conducting in-depth research on the evolution, species identification, and genomic breeding of yellow Camellia.
Genome, Chloroplast/genetics* ; Phylogeny ; Plant Breeding ; Camellia/genetics* ; Chloroplasts/genetics*

Pellionia scabra belongs to the genus Pellionia in the family of Urticaceae, and is a high-quality wild vegetables with high nutritional value. In this study, high-throughput techniques were used to sequence, assemble and annotate the chloroplast genome. We also analyzed its structure, and construct the phylogenetic trees from the P. scabra to further study the chloroplast genome characteristics. The results showed that the chloroplast genome size was 153 220 bp, and the GC content was 36.4%, which belonged to the typical tetrad structure in P. scabra. The chloroplast genome encodes 130 genes, including 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes in P. scabra. Among them, 15 genes contained 1 intron, 2 genes contained 2 introns, and rps12 had trans-splicing, respectively. In P. scabra, chloroplast genomes could be divided into four categories, including 43 photosynthesis, 64 self-replication, other 7 coding proteins, and 4 unknown functions. A total of 51 073 codons were detected in the chloroplast genome, among which the codon encoding leucine (Leu) accounted for the largest proportion, and the codon preferred to use A and U bases. There were 72 simple sequence repeats (SSRs) in the chloroplast genome of P. scabra, containing 58 single nucleotides, 12 dinucleotides, 1 trinucleotide, and 1 tetranucleotide. The ycf1 gene expansion was present at the IRb/SSC boundary. The phylogenetic trees showed that P. scabra (OL800583) was most closely related to Elatostema stewardii (MZ292972), Elatostema dissectum (MK227819) and Elatostema laevissimum var. laevissimum (MN189961). Taken together, our results provide worthwhile information for understanding the identification, genetic evolution, and genomics research of P. scabra species.
Phylogeny ; Genome, Chloroplast/genetics* ; Genomics ; Chloroplasts/genetics* ; Codon ; Urticaceae/genetics*