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Peanut is an important oilseed and a widely cultivated crop worldwide. Knowledge of the phylogenetic relationships and information on the chloroplast genomes of wild and cultivated peanuts is crucial for the evolution of peanuts. In this study, we sequenced and assembled 14 complete chloroplast genomes of Arachis. The total lengths varied from 156,287 bp to 156, 402 bp, and the average guanine–cytosine content was 36.4% in 14 Arachis species. A total of 85 simple sequence repeats (SSRs) loci were detected, including 3 dinucleotide and 82 polynucleotide SSRs. Based on 110 complete chloroplast genomes of Arachis, a phylogenetic tree was constructed, which was divided into two groups (I and II). A total of 79 different genes were identified, of which six double-copy genes (ndhB, rpl2, rpl23, rps7, ycf1, and ycf2) and one triple-copy gene (rps12) are present in all 14 Arachis species, implying that these genes may be critical for photosynthesis. The dN/dS ratios for four genes (rps18, accD, clpP, ycf1) were larger than 1, indicating that these genes are subject to positive selection. These results not only provided rich genetic resources for molecular breeding but also candidate genes for further functional gene research. [ABSTRACT FROM AUTHOR]

Background: Dactylicapnos is a climbing herbaceous vine, distributed from the Himalayas to southwestern China, and some of the species have important medicinal values. However, the chloroplast genomes of Dactylicapnos have never been investigated. In this study, chloroplast genomes of seven Dactylicapnos species covering all three sections and one informal group of Dactylicapnos were sequenced and assembled, and the detailed comparative analyses of the chloroplast genome structure were provided for the first time. Results: The results showed that the chloroplast genomes of Dactylicapnos have a typical quadripartite structure with lengths from 172,344 bp to 176,370 bp, encoding a total of 133–140 genes, containing 88–94 protein-coding genes, 8 rRNAs and 37–39 tRNAs. 31 codons were identified as relative synonymous codon usage values greater than one in the chloroplast genome of Dactylicapnos genus based on 80 protein-coding genes. The results of the phylogenetic analysis showed that seven Dactylicapnos species can be divided into three main categories. Phylogenetic analysis revealed that seven species form three major clades which should be treated as three sections. Conclusions: This study provides the initial report of the chloroplast genomes of Dactylicapnos, their structural variation, comparative genomic and phylogenetic analysis for the first time. The results provide important genetic information for development of medical resources, species identification, infrageneric classification and diversification of Dactylicapnos. [ABSTRACT FROM AUTHOR]

Transfer ribonucleic acids (tRNAs) are small non-coding ribonucleic acids that decode messenger RNA sequences and are directly involved in protein synthesis by carrying amino acids to the ribosome. However, the chloroplast genome needs to better understand tRNAs' phylogeny and evolutionary mechanisms. The present study aimed to delineate the novel structural variations and evolutionary characteristics in the chloroplast genome tRNAs of thirty-six Sapindaceae species. Several novel tRNA structures were identified in the Sapindaceae chloroplast genome. The length of tRNAs ranged from 64 to 93 nucleotides, containing 27–29 anticodons. Pair-wise sequence results showed the conserved nucleotide consensus sequence U-U-C-x-A–x-U in Sapindaceae. The structural analysis revealed that, except for a few tRNAs (tRNAHis, tRNAGly, tRNAThr, tRNAPhe, tRNATry, tRNAMet, and tRNAPro), all contained a G nucleotide at the 1st position in the acceptor's arm of tRNAs secondary structure. The rate of transition and transversion of tRNAs are Iso-acceptor-specific. Evolutionary analysis revealed that Sapindaceae chloroplast tRNAs might have evolved polyphyletically with a high percentage of gene loss. Phylogenetic analysis revealed that the chloroplast genome's tRNAs evolved from several common ancestors. At the same time, tRNAVal and tRNAMet appear to be the ancestral tRNAs that underwent duplication diversification to give rise to other tRNAs. Our findings will help us understand the evolution of the tRNA and suggest a key role in chloroplast tRNA biology. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa) is a perennial forage legume that is widely distributed all over the world; therefore, it has an extremely complex genetic background. Though population structure and phylogenetic studies have been conducted on a large group of alfalfa nuclear genomes, information about the chloroplast genomes is still lacking. Chloroplast genomes are generally considered to be conservative and play an important role in population diversity analysis and species adaptation in plants. Here, 231 complete alfalfa chloroplast genomes were successfully assembled from 359 alfalfa resequencing data, on the basis of which the alfalfa chloroplast pan-genome was constructed. We investigated the genetic variations of the alfalfa chloroplast genome through comparative genomic, genetic diversity, phylogenetic, population genetic structure, and haplotype analysis. Meanwhile, the expression of alfalfa chloroplast genes under cold stress was explored through transcriptome analysis. As a result, chloroplast genomes of 231 alfalfa lack an IR region, and the size of the chloroplast genome ranges from 125,192 bp to 126,105 bp. Using population structure, haplotypes, and construction of a phylogenetic tree, it was found that alfalfa populations could be divided into four groups, and multiple highly variable regions were found in the alfalfa chloroplast genome. Transcriptome analysis showed that tRNA genes were significantly up-regulated in the cold-sensitive varieties, while rps7, rpl32, and ndhB were down-regulated, and the editing efficiency of ycf1, ycf2, and ndhF was decreased in the cold-tolerant varieties, which may be due to the fact that chloroplasts store nutrients through photosynthesis to resist cold. The huge number of genetic variants in this study provide powerful resources for molecular markers. [ABSTRACT FROM AUTHOR]

Background: Cuscuta, a parasitic plant species in the Convolvulaceae family, grows in many countries and regions. However, the relationship between some species is still unclear. Therefore, more studies are needed to assess the variation of the chloroplast (cp) genome in Cuscuta species and their relationship with subgenera or sections, thus, providing important information on the evolution of Cuscuta species. Results: In the present study, we identified the whole cp genomes of C. epithymum, C. europaea, C. gronovii, C. chinensis and C. japonica, and then constructed a phylogenetic tree of 23 Cuscuta species based on the complete genome sequences and protein-coding genes. The complete cp genome sequences of C. epithymum and C. europaea were 96,292 and 97,661 bp long, respectively, and lacked an inverted repeat region. Most cp genomes of Cuscuta spp. have tetragonal and circular structures except for C. epithymum, C. europaea, C. pedicellata and C. approximata. Based on the number of genes and the structure of cp genome and the patterns of gene reduction, we found that C. epithymum and C. europaea belonged to subgenus Cuscuta. Most of the cp genomes of the 23 Cuscuta species had single nucleotide repeats of A and T. The inverted repeat region boundaries among species were similar in the same subgenera. Several cp genes were lost. In addition, the numbers and types of the lost genes in the same subgenus were similar. Most of the lost genes were related to photosynthesis (ndh, rpo, psa, psb, pet, and rbcL), which could have gradually caused the plants to lose the ability to photosynthesize. Conclusion: Our results enrich the data on cp. genomes of genus Cuscuta. This study provides new insights into understanding the phylogenetic relationships and variations in the cp genome of Cuscuta species. [ABSTRACT FROM AUTHOR]

Background: Toxicodendron vernicifluum, belonging to the family Anacardiaceae, is an important commercial arbor species, which can provide us with the raw lacquer, an excellent adhesive and painting material used to make lacquer ware. Compared with diploid, triploid lacquer tree has a higher yield of raw lacquer and stronger resistance to stress. Triploid T. vernicifluum was a newly discovered natural triploid lacquer tree. However, the taxonomy of triploid T. vernicifluum has remained uncertain. Here, we sequenced and analyzed the complete chloroplast (cp) genome of triploid T. vernicifluum and compared it with related species of Toxicodendron genus based on chloroplast genome and SSR markers. Results: The plastome of triploid T. vernicifluum is 158,221 bp in length, including a pair of inverted repeats (IRs) of 26,462 bp, separated by a large single-copy region of 86,951 bp and a small single-copy region of 18,346 bp. In total, 132 genes including 87 protein-coding genes, 37 tRNA genes and 8 rRNA genes were identified in the triploid T. vernicifluum. Among these, 16 genes were duplicated in the IR regions, 14 genes contain one intron, while three genes contain two introns. After nucleotide substitutions, seven small inversions were analyzed in the chloroplast genomes, eight hotspot regions were found, which could be useful molecular genetic markers for future population genetics. Phylogenetic analyses showed that triploid T. vernicifluum was a sister to T. vernicifluum cv. Dahongpao and T. vernicifluum cv. Hongpigaobachi. Moreover, phylogenetic clustering based on the SSR markers showed that all the samples of triploid T. vernicifluum, T. vernicifluum cv. Dahongpao and T. vernicifluum cv. Hongpigaobachi in one group, while the samples of T. vernicifluum and T. succedaneum in another group, which is consistent with the cp genome and morphological analysis. Conclusions: The current genomic datasets provide pivotal genetic resources to determine the phylogenetic relationships, variety identification, breeding and resource exploitation, and future genetic diversity-related studies of T. vernicifluum. [ABSTRACT FROM AUTHOR]

The tree Cryptomeria japonica var. sinensis is native to China and is an important forest species widely used for wood production. Here, we sequenced the complete chloroplast (cp) genomes of six wild and six cultivated accessions of this tree. The 12 cp genomes ranged from 131,379 to 131,528 bp. The GC content was 35.4%, similar to other gymnosperm species. The cp genomes lacked typical inverted repeat (IR) regions and encoded 118 genes. Most genes appeared in one copy and 17 genes contained introns. Two multi-copy genes (trnM-CAU × 3, trnQ-UUG × 2) were identified. And 59–61 simple sequence repeats (SSRs) were identified in the whole cp genomes, and most SSR loci consisted of A or T bases. Phylogenetic analysis indicated that wild and cultivated accessions were not clearly differentiated. Our results will provide useful information for the conservation and utilization of this variety. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1932592. [ABSTRACT FROM AUTHOR]

Camellia oleifera is one of the four largest woody edible oil plants in the world with high ecological and medicinal values. Due to frequent interspecific hybridization, it was difficult to study its genetics and evolutionary history. This study used C. oleifera that was collected on Hainan Island to conduct our research. The unique island environment makes the quality of tea oil higher than that of other species grown in the mainland. Moreover, a long-term geographic isolation might affect gene structure. In order to better understand the molecular biology of this species, protect excellent germplasm resources, and promote the population genetics and phylogenetic studies of Camellia plants, high-throughput sequencing technology was used to obtain the chloroplast genome sequence of Hainan C. oleifera. The results showed that the whole chloroplast genome of C. oleifera in Hainan was 156,995 bp in length, with a typical quadripartite structure of a large single copy (LSC) region of 86,648 bp, a small single copy (SSC) region of 18,297 bp, and a pair of inverted repeats (IRs) of 26,025 bp. The whole genome encoded a total of 141 genes (115 different genes), including 88 protein-coding genes, 45 tRNA genes, and eight rRNA genes. Among these genes, nine genes contained one intron, two genes contained two introns, and four overlapping genes were also detected. The total GC content of Hainan C. oleifera’s chloroplast genome was 37.29%. The chloroplast genome structure characteristics of Hainan C. oleifera were compared with mainland C. oleifera and those of the other eight closely related Theaceae species; it was found that the contractions and expansions of the IR/LSC and IR/SSC regions affected the length of chloroplast genome. The chloroplast genome sequences of these Theaceae species were highly similar. A comparative analysis indicated that the Theaceae species were conserved in structure and evolution. A total of 51 simple sequence repeat (SSR) loci were detected in the chloroplast genome of Hainan C. oleifera, and all Camellia plants did not have pentanucleotide repeats, which could be used as a good marker in phylogenetic studies. We also detected seven long repeats, the base composition of all repeats was biased toward A/T, which was consistent with the codon bias. It was found that Hainan C. oleifera had a similar evolutionary relationship with C. crapnelliana, through the use of codons and phylogenetic analysis. This study can provide an effective genomic resource for the evolutionary history of Theaceae family. [ABSTRACT FROM AUTHOR]

Pigeonpea (Cajanus cajan (L.) Millspaugh), a diploid (2n=22) legume crop with a genome size of 852 Mbp, serves as an important source of human dietary protein especially in South East Asian and African regions. In this study, the draft chloroplast genomes of Cajanus cajan and Cajanus scarabaeoides (L.) Thouars were generated. Cajanus scarabaeoides is an important species of the Cajanus gene pool and has also been used for developing promising CMS system by different groups. A male sterile genotype harboring the C. scarabaeoides cytoplasm was used for sequencing the plastid genome. The cp genome of C. cajan is 152,242bp long, having a quadripartite structure with LSC of 83,455 bp and SSC of 17,871 bp separated by IRs of 25,398 bp. Similarly, the cp genome of C. scarabaeoides is 152,201bp long, having a quadripartite structure in which IRs of 25,402 bp length separates 83,423 bp of LSC and 17,854 bp of SSC. The pigeonpea cp genome contains 116 unique genes, including 30 tRNA, 4 rRNA, 78 predicted protein coding genes and 5 pseudogenes. A 50 kb inversion was observed in the LSC region of pigeonpea cp genome, consistent with other legumes. Comparison of cp genome with other legumes revealed the contraction of IR boundaries due to the absence of rps19 gene in the IR region. Chloroplast SSRs were mined and a total of 280 and 292 cpSSRs were identified in C. scarabaeoides and C. cajan respectively. RNA editing was observed at 37 sites in both C. scarabaeoides and C. cajan, with maximum occurrence in the ndh genes. The pigeonpea cp genome sequence would be beneficial in providing informative molecular markers which can be utilized for genetic diversity analysis and aid in understanding the plant systematics studies among major grain legumes. [ABSTRACT FROM AUTHOR]

Chloroplast (cp) genome sequences become a useful popular tool for population and phylogeny in recent reports. Here, the complete chloroplast genome of the Fagopyrum dibotrys has been reconstructed from the whole-genome Illumina sequencing data. The circular genome is 159,325 bp in size, and comprises a pair of inverted repeat (IR) regions of 67,788 bp each, a large single-copy (LSC) region of 84,593 bp, and a small single-copy (SSC) region of 6,944 bp. The total Guanine and Cytosine (GC) content is 38.0%, while the corresponding values of the LSC, SSC, and IR region are 36.3%, 34.5%, and 40.2%, respectively. The chloroplast genome contains 131 genes, including 94 protein-coding genes, eight ribosomal RNA genes, and 29 transfer RNA genes. The Maximum-Likelihood Phylogenetic analysis showed a strong sister relationship with F. tataricum in Polygonaceae. Our findings provide a foundation for further investigation of cp genome evolution in F. dibotrys and other higher plants. [ABSTRACT FROM AUTHOR]

Retrophyllum piresii (Podocarpaceae) is an endemic conifer species from the Brazilian Amazonian Region, and very few data related to ecological and genetic characteristics of this species are available. Plastome sequencing is an efficient tool to understand enigmatic and basal phylogenetic relationships at different taxonomic levels, as well as to probe the structural and functional evolution of plants. Usually, the plastome of photosynthetic land plants is quadripartite, with two copies of the inverted repeats (IRs) separating the small and large single-copy regions. However, in gymnosperms, IR can vary from large in size to completely absent, being constituted principally by transfer RNA (tRNA) genes, or a part of sequence of other genes. Here, we sequenced and characterized the complete plastome of R. piresii. This plastome was determined to be 133,291 bp (~480-fold coverage), presenting a total of 120 identified genes, of which 118 were single copy and two genes, trnN-GUU and trnD-GUC, were found to be duplicated and occurring as inverted and directed repeat (DR) sequences, respectively. These repeated regions presented recombinationally active sites, resulting in an IR-mediated inversion and a DR-mediated deletion. However, the isoform resulted from DR-mediated deletion may result in unviable plastome, with deletion of photosynthetic and expression machinery-related genes. [ABSTRACT FROM AUTHOR]

Studies on chloroplast genomes of ferns and lycophytes are relatively few in comparison with those on seed plants. Although a basic phylogenetic framework of extant ferns is available, relationships among a few key nodes remain unresolved or poorly supported. The primary objective of this study is to explore the phylogenetic utility of large chloroplast gene data in resolving difficult deep nodes in ferns. We sequenced the chloroplast genomes from Cyrtomium devexiscapulae (Koidz.) Ching (eupolypod I) and Woodwardia unigemmata (Makino) Nakai (eupolypod II), and constructed the phylogeny of ferns based on both 48 genes and 64 genes. The trees based on 48 genes and 64 genes are identical in topology, differing only in support values for four nodes, three of which showed higher support values for the 48-gene dataset. Equisetum L. was resolved as the sister to the Psilotales-Ophioglossales clade, and Equisetales-Psilotales-Ophioglossales clade was sister to the clade of the leptosporangiate and marattioid ferns. The sister relationship between the tree fern clade and polypods was supported by 82% and 100% bootstrap values in the 64-gene and 48-gene trees, respectively. Within polypod ferns, Pteridaceae was sister to the clade of Dennstaedtiaceae and eupolypods with a high support value, and the relationship of Dennstaedtiaceae-eupolypods was strongly supported. With recent parallel advances in the phylogenetics of ferns using nuclear data, chloroplast phylogenomics shows great potential in providing a framework for testing the impact of reticulate evolution in the early evolution of ferns. [ABSTRACT FROM AUTHOR]

To date, publicly available plastid genomes of legumes have for the most part been limited to the subfamily Papilionoideae. Here we report 13 new plastid genomes of legumes spanning all three subfamilies. The genomes representing Caesalpinioideae and Mimosoideae are highly conserved in gene content and gene order, similar to the ancestral angiosperm genome organization. Genomes within the Papilionoideae, however, have reduced sizes due to deletions in nine intergenic spacers primarily in the large single copy region. Our study also indicates that rps16 has been independently lost at least five times in legumes, with additional gene and intron losses scattered among the papilionoids. Additionally, genera from two distinct lineages within the papilionoids, Lupinus and Robinia, have a parallel inversion of 36 and 39 kb, respectively. This parallel inversion is novel as it appears to be caused by a 29 bp repeat within two trnS genes. This repeat is present in all available legume plastid genomes indicating that there is the potential for this inversion to be present in more species. This case of a homoplasious inversion is also evidence that some inversion events may not be reliable phylogenetic markers. [ABSTRACT FROM AUTHOR]

Metasequoia glyptostroboides Hu et Cheng is the only species in the genus Metasequoia Miki ex Hu et Cheng, which belongs to the Cupressaceae family. There were around 10 species in the Metasequoia genus, which were widely spread across the Northern Hemisphere during the Cretaceous of the Mesozoic and in the Cenozoic. M. glyptostroboides is the only remaining representative of this genus. Here, we report the complete chloroplast (cp) genome sequence and the cp genomic features of M. glyptostroboides. The M. glyptostroboides cp genome is 131,887 bp in length, with a total of 117 genes comprised of 82 protein-coding genes, 31 tRNA genes and four rRNA genes. In this genome, 11 forward repeats, nine palindromic repeats, and 15 tandem repeats were detected. A total of 188 perfect microsatellites were detected through simple sequence repeat (SSR) analysis and these were distributed unevenly within the cp genome. Comparison of the cp genome structure and gene order to those of several other land plants indicated that a copy of the inverted repeat (IR) region, which was found to be IR region A (IRA), was lost in the M. glyptostroboides cp genome. The five most divergent and five most conserved genes were determined and further phylogenetic analysis was performed among plant species, especially for related species in conifers. Finally, phylogenetic analysis demonstrated that M. glyptostroboides is a sister species to Cryptomeria japonica (L. F.) D. Don and to Taiwania cryptomerioides Hayata. The complete cp genome sequence information of M. glyptostroboides will be great helpful for further investigations of this endemic relict woody plant and for in-depth understanding of the evolutionary history of the coniferous cp genomes, especially for the position of M. glyptostroboides in plant systematics and evolution. [ABSTRACT FROM AUTHOR]

The chloroplast genome (cp genome) of Aconitum barbatum var. puberulum was sequenced using the third-generation sequencing platform based on the single-molecule real-time (SMRT) sequencing approach. To our knowledge, this is the first reported complete cp genome of Aconitum, and we anticipate that it will have great value for phylogenetic studies of the Ranunculaceae family. In total, 23,498 CCS reads and 20,685,462 base pairs were generated, the mean read length was 880 bp, and the longest read was 2,261 bp. Genome coverage of 100% was achieved with a mean coverage of 132× and no gaps. The accuracy of the assembled genome is 99.973%; the assembly was validated using Sanger sequencing of six selected genes from the cp genome. The complete cp genome of A. barbatum var. puberulum is 156,749 bp in length, including a large single-copy region of 87,630 bp and a small single-copy region of 16,941 bp separated by two inverted repeats of 26,089 bp. The cp genome contains 130 genes, including 84 protein-coding genes, 34 tRNA genes and eight rRNA genes. Four forward, five inverted and eight tandem repeats were identified. According to the SSR analysis, the longest poly structure is a 20-T repeat. Our results presented in this paper will facilitate the phylogenetic studies and molecular authentication on Aconitum. [ABSTRACT FROM AUTHOR]

The loss of a gene is a rare genome-shaping event and as such, contributes important information to our understanding of phylogenetic relationships between genes and between species. Deletion of a gene can help to define a lineage. Here, we utilize the deletion of the chloroplast gene encoding the acetyl-CoA carboxylase subunit D ( accD) to help us define lineages based on its presence or absence in monocot plants specifically in Poales. Southern blots were constructed and probed for the presence of the accD gene. The existence of the portion of the accD gene represented by the probe was also verified by PCR and sequencing. Sequences were utilized for assembly of gene trees to link the absence or partial loss of the gene with a particular lineage. Here, we report new information adding accD gene presence in the Xyridaceae, pseudogene presence in the Flagellariaceae, and the absence of accD in Restionaceae and Joinvilleaceae. Based on our findings and the available data for accD sequences in Poales, we propose a model for accD loss beginning with a single event creating a pseudogene in the common ancestor to the restiid and graminid clades within Poales. This model also suggests that this pseudogene is carried as the ancestral state throughout most of the divergence of the Poales, a condition that would explain the highly varied pattern of accD pseudogene presence or gene absence in members of the restiid and graminid clades. [ABSTRACT FROM AUTHOR]

The rpoA gene coding for the α-subunit of DNA-dependent RNA polymerase located in the chloroplastic genome of date palm has been characterized from the elite cultivar Deglet Nour by cloning and sequencing of the PCR amplification product. The full length of rpoA-Pd ( Phoenix dactylifera) gene was 1014 bp. The comparison in Genbank showed that the rpoA gene has a 100% homology with the Khalas cultivar of date palm and a strong homology with Oil Palm (99%). The deduced protein full length is 337 amino acid corresponding to 38,692 Da polypeptide. It contained an Alpha N-terminal domain (alpha-NTD) between 1 to 233 (aa) and Alpha C-terminal domain (alpha-CTD) between 266 to 337 (aa). Initially, we have compared the sequences of the full-length DNA rpoA gene from Date Palm and Oil palm, 15 mutations have been detected, 4 do not affect amino acid sequences. A multiple alignment of protein sequences of Date Palm and other plants shows 6 mutations specific for palms family and one is specific to monocots species. A multiple alignment of 35 nucleotide sequences from different plant species shows 3 SNPs specific to Date Palm, 6 SNPs specific to Palms family and 6 other to monocot species. The phylogenetic analysis performed in this work shows a strong similarity between Pd-rpoA and rpoA genes from other plant species, but it shows a great divergence with the rpoA of E. coli. To explain whether the separation of the two clades was due to selection pressure. We calculate the ratio Ka/ Ks for different species. A synteny analyses of rpoA genes was effected, a high genomic synteny is observed for the ropA in all the species included in this study. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequence of the rapeseed ( Brassica napus L.) chloroplast genome (cpDNA) was determined. The 152,860 bp cpDNA contained a pair of 26,035 bp inverted repeat regions (IR), which are separated by small and large single copy regions (SSC and LSC) of 83,030 and 17,760 bp, respectively. The major portion (56.4%) of the B. napus cpDNA consists of gene coding regions, while intergenic spacers make up 43.6% of the complete genome. The average AT content of the B. napus cpDNA is 63.7% and for the LSC, SSC and IR region is 65.9, 70.8 and 57.7%, respectively. Fifteen genes contained one intron, while three genes had two introns. In total, 86 simple sequence repeats were identified. The detailed comparison of the B. napus with one of its putative parents, B. rapa L. cpDNA indicated that the two species were highly similar. The entire gene pool and relative positions of 113 individual genes were identical to those of B. rapa cpDNA. The sequence divergence analysis of B. napus and B. rapa showed only 0.133% in the coding regions, 0.275% in the intron regions, and 0.348% in the intergenic spacer regions. The phylogenies based on 61 protein coding genes from 48 cpDNA sequences provided strong support for monophyly of many major classes of angiosperms and provided support that Amborella could be a sister to all other angiosperms. Our analysis also supported that B. napus is the closest species to B. rapa and B. rapa could be the mathernal parent of B. napus cv. zy036. [ABSTRACT FROM AUTHOR]

Pinaceae, the largest family of conifers, has diversified organizations of chloroplast genomes (cpDNAs) with the two typical inverted repeats (IRs) highly reduced. To unravel the mechanism of this genomic diversification, we examined the cpDNA organizations from 53 species of the ten Pinaceous genera, including those of Larix decidua (122,474 bp), Picea morrisonicola (124,168 bp), and Pseudotsuga wilsoniana (122,513 bp), which were firstly elucidated. The results uncovered four distinct cpDNA forms (A−C and P) that are due to rearrangements of two ∼20 and ∼21 kb specific fragments. The C form was documented for the first time and the A form might be the most ancestral one. In addition, only the individuals of Ps. macrocarpa and Ps. wilsoniana were detected to have isomeric cpDNA forms. Three types (types 1−3) of Pinaceae-specific repeats situated nearby the rearranged fragments were found to be syntenic. We hypothesize that type 1 (949 ± 343 bp) and type 3 (608 ± 73 bp) repeats are substrates for homologous recombination (HR), whereas type 2 repeats are likely inactive for HR because of their relatively short sizes (151 ± 30 bp). Conversions among the four distinct forms may be achieved by HR and mediated by type 1 or 3 repeats, thus resulting in increased diversity of cpDNA organizations. We propose that in the Pinaceae cpDNAs, the reduced IRs have lost HR activity, then decreasing the diversity of cpDNA organizations, but the specific repeats that the evolution endowed Pinaceae complement the reduced IRs and increase the diversity of cpDNA organizations. [ABSTRACT FROM AUTHOR]

Mungbean is an economically important crop which is grown principally for its protein-rich dry seeds. However, genomic research of mungbean has lagged behind other species in the Fabaceae family. Here, we reported the complete chloroplast (cp) genome sequence of mungbean obtained by the 454 pyrosequencing technology. The mungbean cp genome is 151 271 bp in length which includes a pair of inverted repeats (IRs) of 26 474 bp separated by a small single-copy region of 17 427 bp and a large single-copy region of 80 896 bp. The genome contains 108 unique genes and 19 of these genes are duplicated in the IR. Of these, 75 are predicted protein-coding genes, 4 ribosomal RNA genes and 29 tRNA genes. Relative to other plant cp genomes, we observed two distinct rearrangements: a 50-kb inversion between accD/rps16 and rbcL/trnK-UUU, and a 78-kb rearrangement between trnH/rpl14 and rps19/rps8. We detected sequence length polymorphism in the cp homopolymeric regions at the intra- and inter-specific levels in the Vigna species. Phylogenetic analysis demonstrated a close relationship between Vigna and Phaseolus in the phaseolinae subtribe and provided a strong support for a monophyletic group of the eurosid I. [ABSTRACT FROM PUBLISHER]

The structure of the junction between inverted repeat (IR) and small single copy (SSC) regions of the chloroplast genome in the representatives of non-core Caryophyllales is investigated in this work. It was found that for two families—Polygonaceae and Plumbaginaceae—the extension of inverted region is characteristic. This extension is due to the duplication of the part of the ycf1 gene that is partly located in the small single copy region in plants with typical structure of IR/SSC junctions. Comparison of the position of IR/SSC junctions in different species of Polygonaceae has shown that their exact position is not correlated with the affinity of these species inferred from molecular and morphological data. Possible mechanisms leading to the change in position of IR/SSC junctions observed in this work are discussed. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequence of the duckweed ( Lemna minor) chloroplast genome (cpDNA) was determined. The cpDNA is a circular molecule of 165,955 bp containing a pair of 31,223-bp inverted repeat regions (IRs), which are separated by small and large single-copy regions of 89,906 and 13,603 bp, respectively. The entire gene pool and relative positions of 112 genes (78 protein-encoding genes, 30 tRNA genes, and 4 rRNA genes) are almost identical to those of Amborella trichopoda cpDNA; the minor difference is the absence of infA and ycf15 genes in the duckweed cpDNA. The inverted repeat is expanded to include ycf1 and rps15 genes; this pattern is unique and does not occur in any other sequenced cpDNA of land plants. As in basal angiosperms and eudicots, but not in other monocots, the borders between IRs and a large single-copy region are located upstream of rps19 and downstream of trnH, so that trnH is not included in IRs. The model of rearrangements of the chloroplast genome during the evolution of monocots is proposed as the result of the comparison of cpDNA structures in duckweed and other monocots. The phylogenetic analyses of 61 protein-coding genes from 38 plastid genome sequences provided strong support for the monophyly of monocots and position of Lemna as the next diverging lineage of monocots after Acorales. Our analyses also provided support for Amborella as a sister to all other angiosperms, but in the bayesian phylogeny inference based on the first two codon positions Amborella united with Nymphaeales. [ABSTRACT FROM AUTHOR]

Plant cells possess two more genomes besides the central nuclear genome: the mitochondrial genome and the chloroplast genome (or plastome). Compared to the gigantic nuclear genome, these organelle genomes are tiny and are present in high copy number. These genomes are less prone to recombination and, therefore, retain signatures of their age to a much better extent than their nuclear counterparts. Thus, they are valuable phylogenetic tools, giving useful information about the relative age and relatedness of the organisms possessing them. Unlike animal cells, mitochondrial genomes of plant cells are characterized by large size, extensive intramolecular recombination and low nucleotide substitution rates and are of limited phylogenetic utility. Chloroplast genomes, on the other hand, show resemblance to animal mitochondrial genomes in terms of phylogenetic utility and are more relevant and useful in case of plants. Conservation in gene order, content and lack of recombination make the plastome an attractive tool for plant phylogenetic studies. Their importance is reflected in the rapid increase in the availability of complete chloroplast genomes in the public databases. This review aims to summarize the progress in chloroplast genome research since its inception and tries to encompass all related aspects. Starting with a brief historical account, it gives a detailed account of the current status of chloroplast genome sequencing and touches upon RNA editing, ycfs, molecular phylogeny, DNA barcoding as well as gene transfer to the nucleus. [ABSTRACT FROM AUTHOR]

With the completion of the first gymnosperm mitochondrial genome (mtDNA) from Cycas taitungensis and the availability of more mtDNA taxa in the past 5 years, we have conducted a systematic analysis of DNA transfer from chloroplast genomes (cpDNAs) to mtDNAs (mtpts) in 11 plants, including 2 algae, 1 liverwort, 1 moss, 1 gymnosperm, 3 monocots, and 3 eudicots. By using shared gene order and boundaries between different mtpts as the criterion, the timing of cpDNA transfer during plant evolution was estimated from the phylogenetic tree reconstructed independently from concatenated protein-coding genes of 11 available mtDNAs. Several interesting findings emerged. First, frequent DNA transfer from cpDNA to mtDNA occurred at least as far back as the common ancestor of extant gymnosperms and angiosperms, about 300 MYA. The oldest mtpt is trnV(uac)-trnM(cau)-atpE-atpB-rbcL. Three other mtpts—psaA-psaB, rps19-trnH(gug)-rpl2-rpl23, and psbE-psbF—were dated to the common ancestor of extant angiosperms, at least 150 MYA. However, all protein-coding genes of mtpts have degenerated since their first transfer. Therefore, mtpts contribute nothing to the functioning of mtDNA but junk sequences. We discovered that the cpDNA transfers have occurred randomly at any positions of the cpDNAs. We provide strong evidence that the cp-derived tRNA-trnM(cau) is the only mtpt (1 out of 3 cp-derived tRNA shared by seed plants) truly transferred from cpDNA to mtDNA since the time of the common ancestor of extant gymnosperms and angiosperms. Our observations support the proposition of Richly and Leister (2004) that “primary insertions of organellar DNAs are large and then diverge and fragment over evolutionary time.” [ABSTRACT FROM PUBLISHER]

The chloroplast genome sequence of Coffea arabica L., the first sequenced member of the fourth largest family of angiosperms, Rubiaceae, is reported. The genome is 155 189 bp in length, including a pair of inverted repeats of 25 943 bp. Of the 130 genes present, 112 are distinct and 18 are duplicated in the inverted repeat. The coding region comprises 79 protein genes, 29 transfer RNA genes, four ribosomal RNA genes and 18 genes containing introns (three with three exons). Repeat analysis revealed five direct and three inverted repeats of 30 bp or longer with a sequence identity of 90% or more. Comparisons of the coffee chloroplast genome with sequenced genomes of the closely related family Solanaceae indicated that coffee has a portion of rps19 duplicated in the inverted repeat and an intact copy of infA. Furthermore, whole-genome comparisons identified large indels (> 500 bp) in several intergenic spacer regions and introns in the Solanaceae, including trnE (UUC)– trnT (GGU) spacer, ycf4– cemA spacer, trnI (GAU) intron and rrn5– trnR (ACG) spacer. Phylogenetic analyses based on the DNA sequences of 61 protein-coding genes for 35 taxa, performed using both maximum parsimony and maximum likelihood methods, strongly supported the monophyly of several major clades of angiosperms, including monocots, eudicots, rosids, asterids, eurosids II, and euasterids I and II. Coffea (Rubiaceae, Gentianales) is only the second order sampled from the euasterid I clade. The availability of the complete chloroplast genome of coffee provides regulatory and intergenic spacer sequences for utilization in chloroplast genetic engineering to improve this important crop. [ABSTRACT FROM AUTHOR]

Microstructural changes such as insertions and deletions (=indels) are a major driving force in the evolution of non-coding DNA sequences. To better understand the mechanisms by which indel mutations arise, as well as the molecular evolution of non-coding regions, the number and pattern of indels and nucleotide substitutions were compared in the whole chloroplast genomes. Comparisons were made for a total of over 38 kb non-coding DNA sequences from 126 intergenic regions in two data sets representing species with different divergence times: sugarcane and maize and Oryza sativa var. indica and japonica. The main findings of this study are: (i) Approximately half of all indels are single nucleotide indels. This observation agrees with previous studies in various organisms. (ii) The distribution and number of indels was different between two data sets, and different patterns were observed for tandem repeat and non-repeat indels. (iii) Distribution pattern of tandem repeat indels showed statistically significant bias towards A/T-rich. (iv) The rate of indel mutation was estimated to be ≈0.8 ± 0.04 × 10−9 per site per year, which was similar to previous estimates in other organisms. (v) The frequencies of nucleotide substitutions and indels were significantly lower in inverted repeat (IR). [ABSTRACT FROM PUBLISHER]

The complete nucleotide sequence of the chloroplast genome of sugarcane (Saccharum officinarum) was determined. It consists of 141,182 base-pairs (bp), containing a pair of inverted repeat regions (IRA, IRB) of 22,794 bp each. The IRA and IRB sequences separate a small single copy region (12,546 bp) and a large single copy (83,048 bp) region. The gene content and relative arrangement of the 116 identified genes (82 peptide-encoding genes, four ribosomal RNA genes, 30 tRNA genes), with the 16ycfgenes, are highly similar to maize. Editing events, defined as C-to-U transitions in the mRNA sequences, were comparable with those observed in maize, rice and wheat. The conservation of gene organization and mRNA editing suggests a common ancestor for the sugarcane and maize plastomes. These data provide the basis for functional analysis of plastid genes and plastid metabolism within the Poaceae. The sugarcane chloroplast DNA sequence is available at GenBank under accession NC005878. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequence of the chloroplast genome of sugarcane (Saccharum offcinarum) has been determined. It is a circular double-stranded DNA molecule, 141,182 bp in size, and is composed of a large single copy of 83,048 bp, a small single copy of 12,544 bp, and a pair of inverted repeat regions of 22,795 bp each. A comparative analysis among monocots showed that the sugarcane chloroplast genome was very similar to maize but not to rice or wheat. Between sugarcane and maize at the rps16–trnQ (UUG) region, however, a length polymorphism was identified. With regard to insertions/deletions equal to or longer than 5 bp, a total of 53 insertion and 31 deletion events were identified in the sugarcane chloroplast genome. Of the 84 loci identified, a pair of direct repeat sequences was located side by side in a tandem fashion in 47 loci (56.0%). A recombination event during plant evolution is discussed at two sites between the sugarcane and tobacco chloroplast genomes. [ABSTRACT FROM PUBLISHER]

The nucleotide sequence of the complete chloroplast genome of a basal angiosperm, Calycanthusfertilis, has been determined. The circular 153337 bp long cpDNA is colinear with those of tobacco, Arabidopsis and spinach. A total of 133 predicted genes (115 individual gene species, 18 genes duplicated in the inverted repeats) including 88 potential protein-coding genes (81 gene species), 8 ribosomal RNA genes (4 gene species) and 37 tRNA genes (30 gene species) representing 20 amino acids were identified based on similarity to their homologs from other chloroplast genomes. This is the highest gene number ever registered in an angiosperm plastome. Calycanthus fertilis cpDNA also contains a homolog of the recently discovered mitochondrial ACRS gene. Since no gene transfer from mitochondria to the chloroplast has ever been documented, we investigated the evolutionary affinity of this gene in detail. Phylogenetic analysis of the protein-coding subset of the plastome suggests that the ancient line of Laurales emerged after the split of the angiosperms into monocots and dicots. [ABSTRACT FROM AUTHOR]

Abstract Recent contributions from DNA sequences have revolutionized our concept of systematic relationships in angiosperms. However, parts of the angiosperm tree remain unclear. Previous studies have been based on coding or rDNA regions of relatively conserved genes. A phylogeny for basal angiosperms based on noncoding, fast-evolving sequences of the chloroplast genome region trnT-trnF is presented. The recognition of simple direct repeats allowed a robust alignment. Mutational hot spots appear to be confined to certain sectors, as in two stem-loop regions of the trnL intron secondary structure. Our highly resolved and well-supported phylogeny depicts the New Caledonian Amborella as the sister to all other angiosperms, followed by Nymphaeaceae and an Austrobaileya –Illicium –Schisandra clade. Ceratophyllum is substantiated as a close relative of monocots, as is a monophyletic eumagnoliid clade consisting of Piperales plus Winterales sister to Laurales plus Magnoliales. Possible reasons for the striking congruence between the trnT-trnF based phylogeny and phylogenies generated from combined multi-gene, multi-genome data are discussed. [ABSTRACT FROM AUTHOR]

The genetic differentiation of nuclear, mitochondrial (mt) and chloroplast (cp) genomes was investigated by Southern and PCR analysis using 75 varieties of cultivated rice (Oryza sativa L.) and 118 strains of common wild rice (CWR, Oryza rufipogon Griff.) from ten countries of Asia. The distinguishing differences between the Indica and Japonica cultivars were detected both in the nuclear genome and the cytoplasmic genome, confirming that the Indica–Japonica differentiation is of major importance for the three different classes of genome in cultivated rice. This differentiation was also detected in common wild rice with some differences among the genome compartments and the various regions. For nuclear DNA variation, both Indica-like and Japonica-like types were observed in the Chinese CWR, with the latter more-frequent than the former. No Japonica-like type was found in South Asia, and only two strains of the Japonica-like type were detected in Southeast Asia, thus the Indica-like type is the major type among South and Southeast Asian CWR. For mtDNA, only a few strains of the Japonica-like type were detected in CWR. For cpDNA, the Japonica type was predominant among the CWR strains from China, Bangladesh and Burma, while the Indica type was predominant among the CWR strains from Thailand, Malaysia, Cambodia and Sri Lanka, and both types were found in similar frequencies among the Indian CWR. Altogether, however, the degree of Indica–Japonica differentiation in common wild rice was much-less important than that in cultivated rice. Cluster analyses for nuclear and mitochondrial DNA variation revealed that some CWR strains showed large genetic distances from cultivated rice and formed clusters distinct from cultivated rice. Coincidence in the genetic differentiation between the three different classes of genome was much higher in cultivated rice than in CWR. Among the 75 cultivars, about 3/4 entries were "homoeotype" showing congruent results for nuclear, mt and cpDNA regarding the Indica–Japonica differentiation. In CWR, the proportions of homoeotypes were 5.7%, 15% and 48.8% in China, South Asia and Southeast Asia, respectively. Based on the average genetic distance among all the strains of CWR and cultivated rice for nuclear and mitochondrial genomes, the variability of the nuclear genome was found to be higher than that of the mitochondrial genome. The global pattern based on all genomes shows much-more diversification in CWR than that in cultivated rice. [ABSTRACT FROM AUTHOR]

Two-component regulatory systems that respond to changes in redox potential have recently been discovered in bacteria. 'Redox sensors' are defined as electron carriers which initiate control of gene expression upon oxidation or reduction. 'Redox response regulators' are defined as DNA-binding proteins which modify gene expression as a result of the action of redox sensors. Redox sensors and redox response regulators may comprise a mechanism for feedback control of redox potential in photosynthetic electron transport chains, thereby protecting plants, algae and photosynthetic bacteria from damage caused by electrochemistry operating on inappropriate electron donors and acceptors. Chloroplast redox sensors and redox response regulators, themselves encoded in the nucleus, may place chloroplast gene expression under redox regulatory control. This may account for the persistence, in evolution, of chloroplast genomes, and for the constancy of the sub-set of chloroplast proteins encoded and synthesised in situ. These and other predictions are discussed. [ABSTRACT FROM AUTHOR]

Codon use in the three sequenced chloroplast genomes ( Marchantia, Oryza, and Nicotiana) is examined. The chloroplast has a bias in that codons NNA and NNT are favored over synonymous NNC and NNG codons. This appears to be a consequence of an overall high A + T content of the genome. This pattern of codon use is not followed by the psb A gene of all three genomes and other psb A sequences examined. In this gene, the codon use favors NNC over NNT for twofold degenerate amino acids. In each case the only tRNA coded by the genome is complementary to the NNC codon. This codon use is similar to the codon use by chloroplast genes examined from Chlamydomonas reinhardtii. Since psb A is the major translation product of the chloroplast, this suggests that selection is acting on the codon use of this gene to adapt codons to tRNA availability, as previously suggested for unicellular organisms. [ABSTRACT FROM AUTHOR]

We examined chlL ( frxC) gene evolution using several approaches. Sequences from the chloroplast genome of the fern Polystichum acrostichoides and from the cyanobacterium Synechococcus sp. 7002 were determined and found to be highly conserved. A complete physical map of the fern chloroplast genome and partial maps of other vascular plant taxa show that chlL is located primarily in the small single copy region as in Marchantia polymorpha. A survey of a wide variety of non-angiospermous vascular plant DNAs shows that chlL is widely distributed but has been lost in the pteridophyte Psilotum and (presumably independently) within the Gnetalean gymnosperms. [ABSTRACT FROM AUTHOR]

Light-independent chlorophyll synthesis occurs in some algae, lower plants, and gymnosperms, but not in angiosperms. We have identified a new chloroplast gene, chlB, that is required for the light-independent accumulation of chlorophyll in the green alga Chlamydomonas reinhardtii. The chlB gene was cloned, sequenced, and then disrupted by performing particle gun-mediated chloroplast transformation. The resulting homoplasmic mutant was unable to accumulate chlorophyll in the dark and thus exhibited a 'yellow-in-the-dark' phenotype. The chlB gene encodes a polypeptide of 688 amino acid residues, and is distinct from two previously characterized chloroplast genes ( chlN and chlL) also required for light-independent chlorophyll accumulation in C. reinhardtii. Three unidentified open reading frames in chloroplast genomes of liverwort, black pine, and Chlamydomonas moewusii were also identified as chlB genes, based on their striking sequence similarities to the C. reinhardtii chlB gene. A chlB-like gene is absent in chloroplast genomes of tobacco and rice, consistent with the lack of light-independent chlorophyll synthesis in these plants. Polypeptides encoded by the chloroplast chlB genes also show significant sequence similarities with the bchB gene product of Rhodobacter capsulatus. Comparisons among the chloroplast chlB and the bacterial bchB gene products revealed five highly conserved sequence areas that are interspersed by four stretches of highly variable and probably insertional sequences. [ABSTRACT FROM AUTHOR]

DNA sequencing of a region of the chloroplast genome of the red alga Porphyra umbilicalis revealed an open reading frame of 326 amino acids. Databank searches indicated that this ORF is 34% identical to an E. coli gene ( fabH) encoding β-ketoacyl-carrier protein synthase III. In addition, a leucine tRNA gene ( trnL(GAG)) was detected just downstream. Neither of these genes are encoded on the chloroplast genomes of land plants. [ABSTRACT FROM AUTHOR]

To elucidate the evolutionary relationship between the Spermatophyta, Pteridophyta and Bryophyta, we cloned a fragment of chloroplast DNA from the fern Angiopteris lygodiifolia (Pteridophyta) and determined its nucleotide sequence. The fragment contained the atpB, rbcL, trnR-CCG, dedB and psaI genes. Comparisons of the deduced amino acid and nucleotide sequences of these genes from the three plant groups indicate that Angiopteris sequences are more closely related to those of Bryophyta species (85% identity on average) than to those of seed plants (76% identity on average), supporting a hypothesis that the Bryophyta and Pteridophyta diverged more recently from one another than their common progenitor diverged from that of the Spermatophyta. [ABSTRACT FROM AUTHOR]

A detailed restriction map of the chloroplast genome of the red alga Porphyra purpurea has been constructed. Southern hybridization experiments with cloned or gel-purified restriction fragments and PCR products indicate that the P. purpurea chloroplast genome is approximately 188 kb in size. This circular molecule contains two rRNA-encoding repeats (approximately 4.9 kb) that separate the genome into single-copy regions of 34 kb and 144 kb. Interestingly, these repeats are arranged in a direct orientation. In addition, DNA sequencing of the ends of both repeats revealed that the two rRNA repeats are not identical. No intramolecular recombination between the repeats can be detected. We discuss the possibility that the chloroplast genome of P. purpurea is organized like that of the ancestral chloroplast. [ABSTRACT FROM AUTHOR]

The noncoding DNA region of the chloroplast genome, flanked by the genes rbcL and psaI (ORF36), has been sequenced for seven species of the grass family (Poaceae). This region had previously been observed as a hotspot area for length mutations. Sequence comparison reveals that short duplications, probably resulting from slipped-strand mispairing, account for many small length differences between sequences but that major mutational hotspots are localized in three small areas, two of which show potential secondary structure. Mutation in one of these hotspots appears to be a result of more complex recombination events. All seven species contain a pseudogene for rpl23 and evidence is presented that this pseudogene is being maintained by gene conversion with the functional gene. Different transition/transversion biases and AT contents between the pseudogene and the surrounding noncoding sequences are noted. In the subfamily Panicoideae there is a deletion in which almost 1 kb of ancestral sequence, including the 3′ end of the rpl23 pseudogene, has been replaced by a non-homologous 60-base sequence of unknown origin. Two other deletions of almost the same region have occurred in the grass family. The deleted noncoding region has mutational and compositional properties similar to the rbcL coding sequence and the rpl23 pseudogene. The three independent deletions, as well as the pattern of mutation in the localized hotspots, indicate that such noncoding DNA may be misleading for studies of phylogenetic inference. [ABSTRACT FROM AUTHOR]

We have determined the nucleotide sequence of a 5.3-kb region of the plastid DNA (ptDNA) from the heterotrophic holoparasitic plant Cuscuta reflexa. The cloned area contains genes for the D1-protein (32-kDa protein; psbA), tRNA ( trnH), ORF 740 (homologous to ORF 2280 from Nicotiana tabacum), ORF 77 (homologous to ORF 70), tRNA ( trnL) and a hypothetical ORF 55 which has no homology to any known gene among higher plants. This 5.3-kb area is colinear with a 12.4-kb region of tobacco ptDNA and has therefore undergone several deletions totalling 7.1 kb. Most of the missing nucleotides belong to one large deletion in the ptDNA of C. reflexa of approximately 6.5 kb. This deletion involves two ribosomal protein genes, rpl2 and rpl23, as well as the transfer RNA for Isoleucin ( trnI) and a region encoding 1540 amino-acid residues of an ORF 2280 homologue, as compared to tobacco chloroplast DNA. This is remarkable since the remaining genes, especially the psbA gene, are highly conserved in C. reflexa. Furthermore, we found that the expression of the psbA gene is in the same range as in the autotrophic Ipomoea purpurea which belongs to the same family as Cuscuta (Convolvulaceae). Here we hypothesize a total loss of rpl2 and rpl23 in the entire genome of C. reflexa. The phylogenetic position of, and the evolutionary change of ptDNA from, Cuscuta are discussed. [ABSTRACT FROM AUTHOR]

Although the medicinal properties of Coelogyne spp. have been previously studied, there is little genomic information providing a valuable tool for the plant taxonomy, conservation, and utilization of this genus. This study used the next-generation MiSeq sequencing platform to characterize the chloroplast (cp) genomes of Coelogyne fimbriata and Coelogyne ovalis. The Maximum Likelihood (ML) and Bayesian (BI) methods were employed to confirm the phylogenetic position of two Coelogyne species based on the whole chloroplast genome sequences. Additionally, we developed eight new primers based on the two cp genomes' medium variable regions and evaluated the transferability to another 16 Coelogyne species. We constructed phylogenetic trees including 18 Coelogyne species and four outgroup species using the chloroplast fragments with the ML method. Our results showed that the cp genomes of C. fimbriata and C. ovalis contained a small single-copy region (18,839 and 18,851 bp, respectively) and a large single-copy region (87,606 and 87,759 bp, respectively), separated by two same-length inverted-repeat regions (26,675 bp in C. fimbriata and 26,715 bp C. ovalis, respectively). They all contained 86 protein-coding genes, 38 tRNA genes, and eight rRNA genes, revealing strong structure and gene content similarities. The phylogenetic analysis indicated a close relationship between the genera Coelogyne and Pleione. The newly developed primers revealed good transferability among the Coelogyne taxa and provided enough variable sites to distinguish C. fimbriata and C. ovalis. The two complete cp genomes and the eight new primers of Coelogyne provide new genomic data for further studies on phylogenomics, population genetics, and evolutionary history of Coelogyne taxa. [ABSTRACT FROM AUTHOR]

The plant "False Lily of the Valley", Speirantha gardenii is restricted to south-east China and considered as an endemic plant. Due to its limited availability, this plant was less studied. Hence, this study is focused on its molecular studies, where we have sequenced the complete chloroplast genome of S. gardenii and this is the first report on the chloroplast genome sequence of Speirantha. The complete S. gardenii chloroplast genome is of 156,869 bp in length with 37.6% GC, which included a pair of inverted repeats (IRs) each of 26,437 bp that separated a large single-copy (LSC) region of 85,368 bp and a small single-copy (SSC) region of 18,627 bp. The chloroplast genome comprises 81 protein-coding genes, 30 tRNA and four rRNA unique genes. Furthermore, a total of 699 repeats and 805 simple-sequence repeats (SSRs) markers are identified in the genome. Additionally, KA/KS nucleotide substitution analysis showed that seven protein-coding genes have highly diverged and identified nine amino acid sites under potentially positive selection in these genes. Phylogenetic analyses suggest that S. gardenii species has a closer genetic relationship to the Reineckea, Rohdea and Convallaria genera. The present study will provide insights into developing a lineage-specific marker for genetic diversity and gene evolution studies in the Nolinoideae taxa. [ABSTRACT FROM AUTHOR]

Background: The domestication process of Asian rice (Oryza sativa L.) is complicated. It's well established that Oryza rufipogon is the ancestor of Asian rice, although the number of domestication events still controversial. Recently, numerous types of studies based on rice nuclear genome have been conducted, but the results are quite different. Chloroplasts (cp) are also part of the rice genome and have a conserved cyclic structure that is valuable for plant genetics and evolutionary studies. Therefore, we conducted chloroplast-based studies, aiming to provide more evidence for the domestication of Asian rice. Results: A total of 1389 variants were detected from the chloroplast genomes of 412 accessions obtained through the world. Oryza sativa L. ssp. japonica exhibited slightly less diversity (π) than Oryza sativa L. indica and wild rice. The fixation index values (FST) revealed that indica and japonica exhibited farther genetic distances compared with wild rice. Across cp genome, Tajima's D test demonstrated that different selection sites occurred in Asian rice. Principal component analyses (PCA) and multidimensional scaling (MDS) clearly classify the Asian rice into different groups. Furthermore, introgression patterns identified that indica and japonica shared no introgression events in cp level, and phylogenetic studies showed cultivated rice were well separated from different type of wild rice. Conclusions: Here, we focus on the domestication of Asian rice (indica and japonica). Diversity and phylogenetic analyses revealed some selection characteristics in the chloroplast genome that potentially occurred in different Asian rice during the domestication. The results shown that Asian rice had been domesticated at least twice. In additional, japonica may experience a strong positive selection or bottleneck event during the domestication. [ABSTRACT FROM AUTHOR]

Fokienia hodginsii (Dunn) Henry et Thomas is a relic gymnosperm with broad application value. It is a fit candidate when choosing species for the construction of artificial forests. We determined the complete chloroplast genome sequence of F. hodginsii, which is 129,534 bp in length and encodes 83 protein genes, 33 transfer RNA (tRNA) genes, as well as four ribosomal RNA genes. The GC content of the complete sequence and protein coding regions is 34.8% and 36.2%, respectively. We identified 11 tandem repeats, 11 forward repeats, and three palindromic repeats and classified them by size. Following our microsatellite analysis, a total number of 73 simple sequence repeats were detected, preferentially within the intergenic space. Being a member of Cupressophyta, F. hodginsii owns several common characters; the trnR-CCG gene has been deleted, while the trnI-CAU and trnQ-UUG genes have been duplicated. Moreover, the accD gene, which encodes acetyl-CoA carboxylase, contains 771 codons in F. hodginsii, similar to Cryptomeria japonica (L. F.) D. Don, further supporting the diversity of accD and its size expansion in Cupressophyta. Concerning the loss of inverted repeat (IR) regions, the 86-bp sequence with the duplicated trnI-CAU gene is inferred to be the footprint of IR contraction. Phylogenetically, F. hodginsii is placed as a sister taxon to Chamaecyparis hodginsii (Dunn) Rushforth. This work offers meaningful guidance as well as reference value to the breeding research and improvement of F. hodginsii. Moreover, it gives us a better understanding of the genomic structure and evolutionary history of gymnosperms, especially coniferales. [ABSTRACT FROM AUTHOR]

The whole chloroplast genome of wild rice (Oryza australiensis) is characterized in this study. The genome size is 135,224  bp, exhibiting a typical circular structure including a pair of 25,776  bp inverted repeats (IRa,b) separated by a large single-copy region (LSC) of 82,212  bp and a small single-copy region (SSC) of 12,470  bp. The overall GC content of the genome is 38.95%. 110 unique genes were annotated, including 76 protein-coding genes, 4 ribosomal RNA genes, and 30t RNA genes. Among these, 18 are duplicated in the inverted repeat regions, 13 genes contain one intron, and 2 genes (rps12andycf3) have two introns. [ABSTRACT FROM AUTHOR]