Chloroplast Genome Size Research Articles

The complete chloroplast genome sequence of Gomesa flexuosa

Gomesa flexuosa (Lodd) M.W.Chase & N.H.Williams is a new species of orchid revised in 2009. In this study, the chloroplast genome of G. flexuosa was sequenced to determine its genomic characteristics and phylogenetic relationship with other related species. G. flexuosa has a chloroplast genome size of 147,764 bp, comprising 25,757 bp of two inverted repeat (IR) regions, 83,579 bp of large single-copy (LSC) region, and 12,671 bp of small single-copy (SSC) region. Moreover, the whole genome contains 73 protein-coding genes, 38 tRNA genes, and eight rRNA genes. Phylogenetic analysis showed that G. flexuosa is closely related to Oncidium sphacelatum.

Comparative analysis of the chloroplast genomes of a novel albino tea “Huabai 1” and the traditional albino tea “Huangjinya”

The chloroplast genomes of albino tea variety “Huangjinya” and the newly discovered albino tea resource were analyzed comparatively, and DNA barcodes were used to construct phylogenetic trees between albino tea and other plants in theaceae, aiming to reveal the differences in the albino mechanism between the novel albino tea resource “Huabai 1” and the albino tea variety “Huangjinya” and to clarify the genetic evolutionary relationship between the novel albino tea resource “Huabai 1” and other plants in theaceae from the perspective of chloroplast genome. Studies result have shown that the chloroplast genome size of “Huangjinya” and “Huabai 1” is 158,916 bp, 157,028 bp, respectively, LSC (large single-copy),SSC (small single-copy) and IR (inverted repeat) are 86,654 bp, 86,590 bp,18,277 bp, 16,463 bp, and 27,900 bp, 26,081 bp, respectively for “Huangjinya” and “Huabai 1”, with a total of 113 genes annotated were obtained in the chloroplast genome of both albino tea, these include 84 protein coding genes, 24 tRNA genes and 5 rRNA genes. GC content of chloroplast genome of “Huabai 1” was 37.3%, slightly higher than that of “Huangjinya” (37.22%). The gene composition, classification and codon preference (preferred to use codons ending in A/U) of chloroplast genome in “Huabai 1” were basically the same as that in “Huangjinya”, but the main difference was the length of ycf1 fragment in IR region, the length of “Huabai 1” ycf1 fragment was only 987 bp, while that of “Huangjinya” was 2889 bp. The construction of phylogenetic tree was based on the four DNA barcodes (matK, rbcL, trnH-psbA, and ycf1), and the results showed that ycf1, with the most taxonomic levels, was most suitable for the identification of tea varieties and the interpretation of the evolution of genetic relationships among varieties. Ycf1 cluster showed that the relationship between “Huangjinya” and "Longjing 43″ was closer, and that of “Huabai 1” and "Fuding Dabai" was closer. It is speculated that the two tea varieties “Huangjinya” and "Huabai1″ may come from different ancestors, and thus led their quite different albino mechanism. This research will provide the basis for the revealing the albino molecular mechanism and phylogenetic development of the novel albino tea resource “Huabai 1”.

Comparative Chloroplast Genomics of Seven Endangered Cypripedium Species and Phylogenetic Relationships of Orchidaceae.

The species in the genus Cypripedium (Orchidaceae) are considered endangered, mainly distributed in the temperate regions of the Northern Hemisphere, with high ornamental and economic value. Despite previous extensive studies based on both morphology and molecular data, species and sections relationships within Cypripedium remain controversial. Here, we employed two newly generated Cypripedium chloroplast genomes with five other published genomes to elucidate their genomic characteristics. The two genomes were 162,773–207,142 bp in length and contained 128–130 genes, including 82–84 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. We identified 2,192 simple sequence repeats, 786 large repeat sequences, and 7,929 variable loci. The increase of repeat sequences (simple sequence repeats and large repeat sequences) causes a significant amplification in the chloroplast genome size of Cypripedium. The expansion of the IR region led to the pseudogenization or loss of genes in the SSC region. In addition, we identified 12 highly polymorphic loci (Pi > 0.09) suitable for inferring the phylogeny of Cypripedium species. Based on data sets of whole chloroplast genomes (IRa excluded) and protein-coding sequences, a well-supported phylogenetic tree was reconstructed, strongly supporting the five subfamilies of Orchidaceae and the genus Cypripedium as monophyletic taxa. Our findings also supported that C. palangshanense belonged to sect. Palangshanensia rather than sect. Retinervia. This study also enriched the genomic resources of Cypripedium, which may help to promote the conservation efforts of these endangered species.

Comparative Analysis and Phylogenetic Study of the Chloroplast Genome Sequences of Two Korean Endemic Primula Varieties

Primula comprises many species of horticultural value. In Korea, six species grow in the wild. Yamazaki classified the variety Primula modesta var. fauriei into P. modesta var. hannasanensis and P. modesta var. koreana based on the differences in leaf morphology. We compared the chloroplast genome sequences of the two Korean endemic Primula varieties and found that both had the typical quadripartite structure of angiosperms. The chloroplast genome size of P. modesta var. hannasanensis is 154,772 bp, including an 85,238 bp large single-copy region and a 17,790 bp small single-copy region, whereas that of P. modesta var. koreana is 154,667 bp, including an 85,152 bp large single-copy region and a 17,771 bp small single-copy region. The inverted repeat region is 25,872 bp in both varieties. We predicted 129 genes—84 protein-coding genes, 8 rRNAs, and 37 tRNAs. We identified 536 single-nucleotide polymorphisms and 501 indels between the varieties. Phylogenetic analysis revealed that the two varieties formed a sister group in the clade P. knuthiana–P. stenocalyx. This study will contribute to phylogenetic, taxonomic, and evolutionary studies of the genus Primula; it will also contribute to the analysis of the genetic diversity of the two varieties, and to the development of identification markers.

The complete chloroplast genome sequence of Lindera fragrans (Lauraceae): genome structure and phylogenetic analysis

Lindera fragrans, naturally distributed in southern China, is economic and ecological tree. Its leaves are one of the primary raw materials for processing Hawk tea. Here, we assembled the complete chloroplast genome of L. fragrans using Illumina pair-end sequencing. The chloroplast genome size was 152,739 base pairs (bp) with 39% GC content, containing a pair of inverted repeats (IRA/B) of 20,067 bp, separated by a large- and a small single-copy region (LSC/SSC) of 93,711 bp and 18,894 bp, respectively. The genome encoded 126 genes, including 82 protein-coding, 36 transfer RNA (tRNA), and eight ribosomal RNA (rRNA) genes. Phylogenetic analysis based on chloroplast genome sequences of 22 species suggested that L. fragrans was closely related to species of Lindera genus than other genera in Lauraceae. These results can be a valuable genome resource for further genetics and molecular biology studies.

The complete chloroplast genome of Calyptothecium hookeri (Pterobryaceae, Hypnales)

In this study, the complete chloroplast chloroplast genome of Calyptothecium hookeri was studied and reported. The size of the entire chloroplast genome was 124,401bp in length, comprising of two inverted repeats (IRa and IRb, 9371 bp respectively) separated by one large single copy (LSC: 87,126 bp) and one small single copy (SSC: 18,533 bp). The GC content of the genome sequence was 41.28%. A total of 126 functional genes were predicted, consisting of 82 protein-coding genes, 36 tRNA genes, and eight rRNA genes. Phylogenetic analysis showed that the two Pterobryaceae species C. hookeri and C. recurvulum clustered in one clade, which is sister to the Theliaceae species Myurella julacea.

Chloroplast Genomic Resources and Genetic Divergence of Endangered Species Bretschneidera sinensis (Bretschneideraceae)

Bretschneidera sinensis is an endangered woody species found in East and South China. Comprehensive intraspecies chloroplast genome studies have demonstrated novel genetic resources to assess the genetic variation and diversity of this species. Using genome skimming method, we assembled the whole chloroplast genome of 12 genotypes of B. sinensis from different geographical locations, covering most wild populations. The B. sinensis chloroplast genome size ranged from 158,959 to 159,045 base pairs (bp) and displayed a typical circular quadripartite structure. Comparative analyses of 12 B. sinensis chloroplast genome revealed 33 polymorphic simple sequence repeats (SSRs), 105 polymorphic single nucleotide polymorphisms (SNPs), and 55 indels. Phylogenetic analysis showed that the 12 genotypes were grouped into 2 branches, which is consistent with the geographical distribution (Eastern clade and Western clade). Divergence time estimates showed that the two clades were divergent from 0.6 Ma in the late Pleistocene. Ex situ conservation is essential for this species. In this study, we identified SNPs, indels, and microsatellites of B. sinensis by comparative analyses of chloroplast genomes and determined genetic variation between populations using these genomic markers. Chloroplast genomic resources are also important for further domestication, population genetic, and phylogenetic analysis, possibly in combination with molecular markers of mitochondrial and/or nuclear genomes.

Comprehensive analysis of complete chloroplast genome and phylogenetic aspects of ten Ficus species

BackgroundThe large genus Ficus comprises approximately 800 species, most of which possess high ornamental and ecological values. However, its evolutionary history remains largely unknown. Plastome (chloroplast genome) analysis had become an essential tool for species identification and for unveiling evolutionary relationships between species, genus and other rank groups. In this work we present the plastomes of ten Ficus species.ResultsThe complete chloroplast (CP) genomes of eleven Ficus specimens belonging to ten species were determined and analysed. The full length of the Ficus plastome was nearly 160 kbp with a similar overall GC content, ranging from 35.88 to 36.02%. A total of 114 unique genes, distributed in 80 protein-coding genes, 30 tRNAs, and 4 rRNAs, were annotated in each of the Ficus CP genome. In addition, these CP genomes showed variation in their inverted repeat regions (IR). Tandem repeats and mononucleotide simple sequence repeat (SSR) are widely distributed across the Ficus CP genome. Comparative genome analysis showed low sequence variability. In addition, eight variable regions to be used as potential molecular markers were proposed for future Ficus species identification. According to the phylogenetic analysis, these ten Ficus species were clustered together and further divided into three clades based on different subgenera. Simultaneously, it also showed the relatedness between Ficus and Morus.ConclusionThe chloroplast genome structure of 10 Ficus species was similar to that of other angiosperms, with a typical four-part structure. Chloroplast genome sizes vary slightly due to expansion and contraction of the IR region. And the variation of noncoding regions of the chloroplast genome is larger than that of coding regions. Phylogenetic analysis showed that these eleven sampled CP genomes were divided into three clades, clustered with species from subgenus Urostigma, Sycomorus, and Ficus, respectively. These results support the Berg classification system, in which the subgenus Ficus was further decomposed into the subgenus Sycomorus. In general, the sequencing and analysis of Ficus plastomes, especially the ones of species with no or limited sequences available yet, contribute to the study of genetic diversity and species evolution of Ficus, while providing useful information for taxonomic and phylogenetic studies of Ficus.

The complete chloroplast genome sequence of Magnolia coriacea (Magnoliaceae), a critically endangered endemic to China

Magnolia coriacea, Chang et B. L. (Magnoliaceae) is a critically endangered tree, endemic to Yunnan province, China. In this study, the complete chloroplast genome of M. coriacea was sequenced and analyzed. The total chloroplast genome size of M. coriacea is 160,113 bp, including a pair of inverted repeat regions (IRs, 26,576 bp) separated by a large single-copy (LSC, 88,175 bp) region and a small single-copy region (SSC, 18,786 bp). The complete chloroplast genome contains 86 protein-coding (PCGs), 37 transfer RNA (tRNAs), and 8 ribosomal RNA (rRNAs) genes. The phylogenetic analysis showed that M. coriacea is closely related to M. cathcartii. This study contributes to the bioinformatics on the evolution, genetic, conservation, and molecular biology for future studies of Magnoliaceae.

The complete chloroplast genome sequence of Anaphalis margaritacea var. yedoensis (Asteraceae) and phylogenetic relationships within Gnaphalieae

Anaphalis margaritacea var. yedoensis is a perennial herb adapted to the severe environment of pebbled river banks, where it is frequently found. In this study, we determined the complete chloroplast genome of A. margaritacea var. yedoensis and uncovered its phylogenetic relationships with other members of Gnaphalieae. The total chloroplast genome size of A. margaritaceae var. yedoensis is 153,231 bp, with a large single-copy region (LSC) of 84,981 bp, a small single-copy region (SSC) of 18,481 bp and a pair of inverted repeat (IR) regions of 24,885 bp. A total of 136 genes were annotated, including 39 tRNA genes, 8 rRNA genes, and 89 protein-coding genes. Phylogenetic analysis showed that A. margaritacea var. yedoensis and another Anaphalis species, A. sinica, do not form a monophyletic group, supporting previous phylogenetic studies using some specific regions of cpDNA that showed the genus Anaphalis is non-monophyletic.

The complete chloroplast genome of the Chinese banyan tree Ficus microcarpa

Banyan tree or Ficus microcarpa is a large perennial plant with extraordinary aerial roots from the Moraceae family. In this study, the complete chloroplast genome sequence of F. microcarpa was assembled using PacBio data. The chloroplast genome size is 141,611 bp, consisting of a large single-copy (LSC) region and a small single-copy (SSC) region of 101,835 bp and 9,676 bp, respectively, which are separated by a pair of 15,050 bp inverted repeat (IR) regions. The genome includes 74 protein-coding genes, 43 tRNA genes, and 8 rRNA genes. A phylogenetic tree reconstructed by 25 complete chloroplast genomes reveals that F. microcarpa is mostly related to Ficus racemosa.

The comparative studies of complete chloroplast genomes in Actinidia (Actinidiaceae): novel insights into heterogenous variation, clpP gene annotation and phylogenetic relationships.

The genus Actinidia, also called kiwifruit, is characterized with abundant balanced nutritional metabolites, including exceptionally high vitamin C content. However, the traditional classification could not fully reflect the actual Actinidia species' relationships, which need further revision through more accurate approaches. Compared to the nuclear genome, the chloroplast genome has simple heredity characteristics, conserved genome structure and small size, suitable for deciphering complicated species' phylogenetic relationships. Here, the genome-wide comprehensive comparative analyses were performed over 29 independent chloroplast genomes' sequences derived from 25 Actinidia taxa. The average genome size is 156,673.38bp, with an average 37.20% GC content. The long repeat sequences rather than SSRs (simple sequence repeats) in Actinidia were revealed to be the causal agent leading to the chloroplast genome size expansion. The clpP gene sequences with exon merge and intron deletion were annotated in all the 29 chloroplast genomes tested, which has been previously reported to be lost in Actinidia species. Comprehensive sequence analyses indicated the distinct variation at the clpP gene locus was Actinidiaceae-specific, emerging after the Actinidiaceae-other Ericales species divergence. Four highly divergent sequences (i.e., rps16 ~ trnQ-UUG, rps4 ~ trnT-UGU, petA ~ psbJ, and rps12 ~ psbB) evolved in the LSC (large single-copy) and SSC (small single-copy) regions embodying rps12 ~ psbB (including clpP gene and its up/downstream noncoding sequence) were identified as variation hot spots in Actinidia species. Based on either LSC region alone, combined sequences of LSC and SSC or the whole chloroplast genome sequences, three identical phylogenetic trees of the 25 Actinidia taxa with relatively improved resolution were reconstructed, consistently supporting the reticulate evolutionary lineage in Actinidia. Our findings could help to better understand the evolution characteristics of chloroplast genomes and phylogenetic relationships among Actinidia species.

The complete chloroplast genome of the aromatic tree species Cinnamomum tenuipile Kosterm (Lauraceae)

Cinnamomum tenuipile Kosterm is a precious aromatic tree in Lauraceae. To better determine its phylogenetic location with other Cinnamomum species, the chloroplast genome of C. tenuipile was sequenced. The complete chloroplast genome size is 152,761 bp, consisting of a pair of inverted repeats (IRa/b) with a length of 20,074 bp separated by a large single-copy region (LSC) and a small single-copy region (SSC) which are 93,685 and 18,928 bp, respectively. The overall GC content of the cp genome is 39.16%. The maximum-likelihood phylogenetic tree showed that C. tenuipile is more closely related to C. aromaticum, providing new insight into the evolution of Lauraceae.

The complete chloroplast genome of Impatiens mengtszeana (Balsaminaceae), an endemic species in China

Impatiens mengtszeana is an endemic species in China. In this study, the complete chloroplast genome of I. mengtszeana was sequenced and analyzed. The total chloroplast genome size of I. mengtszeana is 152,928 bp, including a pair of inverted repeat regions (IRs, 26,007 bp) separated by a large single copy (LSC, 83,722 bp) region and a small single copy region (SSC, 17,192 bp). The whole chloroplast genome contains 89 protein-coding genes (PCGs), 37 transfer RNA genes (tRNAs), and eight ribosomal RNA genes (rRNAs). According to the phylogenetic topologies, I. mengtszeana was closely related to I. hawkeri.

Study of the genus Torreya (Taxaceae) based on chloroplast genomes.

Species of the genus Torreya are similar in morphology, and their morphological taxonomic characteristics are not stable because of environmentally induced changes. Therefore, morphology is insufficient for understanding their relationships. Chloroplast genome sequencing technology provides a powerful tool for molecular analysis to get more infomation for classification and identification of Torreya genus. A total of 4 chloroplast genome of Torreya, including T. Parvifolia, T. nucifera, T. fargesii var. Yunnanensis and T. grandis var. jiulongshanensis, were sequenced and annotated. Campartive genome and phylogenetic tree were provided for variation analysis. The chloroplast genome size of the four samples is about 137 kb, the inverted repeat (IR) regions are identified in the genus Torreya. Genome comparison using mVISTA showed high sequence similarity among different species. Regions with divergence in exon regions include accD, ndhB, ndhF, psbA, psbJ, rpl2, rps3, rps16, rps18, ycf1, and ycf2. The phylogenetic tree based on 73 single-copy genes showed a clearer relationships among different species of Torreya. All genomes of the four Torreya species consist of two short IR regions, and results of the phylogenetic analysis concluded that T. parvifolia should be considered as T. fargesii var. yunnanensis or treated as a sister species. T. grandis var. jiulongshanensis should be treated as a variety of T. grandis according to molecular evidence, supporting the originally published proposal.

Comparative genomics and phylogenetic relationships of two endemic and endangered species (Handeliodendron bodinieri and Eurycorymbus cavaleriei) of two monotypic genera within Sapindales

BackgroundHandeliodendron Rehder and Eurycorymbus Hand.-Mazz. are the monotypic genera in the Sapindaceae family. The phylogenetic relationship of these endangered species Handeliodendron bodinieri (Lévl.) Rehd. and Eurycorymbus cavaleriei (Lévl.) Rehd. et Hand.-Mazz. with other members of Sapindaceae s.l. is not well resolved. A previous study concluded that the genus Aesculus might be paraphyletic because Handeliodendron was nested within it based on small DNA fragments. Thus, their chloroplast genomic information and comparative genomic analysis with other Sapindaceae species are necessary and crucial to understand the circumscription and plastome evolution of this family.ResultsThe chloroplast genome sizes of Handeliodendron bodinieri and Eurycorymbus cavaleriei are 151,271 and 158,690 bp, respectively. Results showed that a total of 114 unique genes were annotated in H. bodinieri and E. cavaleriei, and the ycf1 gene contained abundant SSRs in both genomes. Comparative analysis revealed that gene content, PCGs, and total GC content were remarkably similar or identical within 13 genera from Sapindaceae, and the chloroplast genome size of four genera was generally smaller within the family, including Acer, Dipteronia, Aesculus, and Handeliodendron. IR boundaries of the H. bodinieri showed a significant contraction, whereas it presented a notable expansion in E. cavaleriei cp genome. Ycf1, ndhC-trnV-UAC, and rpl32-trnL-UAG-ccsA were remarkably divergent regions in the Sapindaceae species. Analysis of selection pressure showed that there are a few positively selected genes. Phylogenetic analysis based on different datasets, including whole chloroplast genome sequences, coding sequences, large single-copy, small single-copy, and inverted repeat regions, consistently demonstrated that H. bodinieri was sister to the clade consisting of Aesculus chinensis and A. wangii and strongly support Eurycorymbus cavaleriei as sister to Dodonaea viscosa.ConclusionThis study revealed that the cp genome size of the Hippocastanoideae was generally smaller compared to the other subfamilies within Sapindaceae, and three highly divergent regions could be used as the specific DNA barcodes within Sapindaceae. Phylogenetic results strongly support that the subdivision of four subfamilies within Sapindaceae, and Handeliodendron is not nested within the genus Aesculus.

Variation in Plastome Sizes Accompanied by Evolutionary History in Monogenomic Triticeae (Poaceae: Triticeae).

To investigate the pattern of chloroplast genome variation in Triticeae, we comprehensively analyzed the indels in protein-coding genes and intergenic sequence, gene loss/pseudonization, intron variation, expansion/contraction in inverted repeat regions, and the relationship between sequence characteristics and chloroplast genome size in 34 monogenomic Triticeae plants. Ancestral genome reconstruction suggests that major length variations occurred in four-stem branches of monogenomic Triticeae followed by independent changes in each genus. It was shown that the chloroplast genome sizes of monogenomic Triticeae were highly variable. The chloroplast genome of Pseudoroegneria, Dasypyrum, Lophopyrum, Thinopyrum, Eremopyrum, Agropyron, Australopyrum, and Henradia in Triticeae had evolved toward size reduction largely because of pseudogenes elimination events and length deletion fragments in intergenic. The Aegilops/Triticum complex, Taeniatherum, Secale, Crithopsis, Herteranthelium, and Hordeum in Triticeae had a larger chloroplast genome size. The large size variation in major lineages and their subclades are most likely consequences of adaptive processes since these variations were significantly correlated with divergence time and historical climatic changes. We also found that several intergenic regions, such as petN–trnC and psbE–petL containing unique genetic information, which can be used as important tools to identify the maternal relationship among Triticeae species. Our results contribute to the novel knowledge of plastid genome evolution in Triticeae.

Chloroplast Genome Traits Correlate With Organismal Complexity and Ecological Traits in Chlorophyta

A positive relationship between cell size and chloroplast genome size within chloroplast-bearing protists has been hypothesized in the past and shown in some case studies, but other factors influencing chloroplast genome size during the evolution of chlorophyte algae have been less studied. We study chloroplast genome size and GC content as a function of habitats and cell size of chlorophyte algae. The chloroplast genome size of green algae in freshwater, marine and terrestrial habitats was differed significantly, with terrestrial algae having larger chloroplast genome sizes in general. The most important contributor to these enlarged genomes in terrestrial species was the length of intergenic regions. There was no clear difference in the GC content of chloroplast genomes from the three habitats categories. Functional morphological categories also showed differences in chloroplast genome size, with filamentous algae having substantially larger genomes than other forms of algae, and foliose algae had lower GC content than other groups. Chloroplast genome size showed no significant differences among the classes Ulvophyceae, Trebouxiophyceae, and Chlorophyceae, but the GC content of Chlorophyceae chloroplast genomes was significantly lower than that of Ulvophyceae and Trebouxiophyceae. There was a certain positive relationship between chloroplast genome size and cell size for the Chlorophyta as a whole and within each of three major classes. Our data also confirmed previous reports that ancestral quadripartite architecture had been lost many times independently in Chlorophyta. Finally, the comparison of the phenotype of chlorophytes algae harboring plastids uncovered that most of the investigated Chlorophyta algae housed a single plastid per cell.

The chloroplast genome of Elytrigia repens (L.) Nevski (Poaceae: Triticeae), a widespread perennial grass from Qinghai-Tibetan Plateau, China

Elytrigia repens (L.) Nevski, belonging to Triticeae of Poaceae, is a wild-growing perennial grass, widely distributed in Qinghai-Tibetan Plateau of China. In this study, the complete chloroplast genome of E. repens was sequenced and analyzed. The complete chloroplast genome size is 134,749 bp with 38.3% GC content. It includes 136 genes, including 89 protein-coding genes, 39 tRNAs genes, and 8 rRNAs genes. Based on chloroplast genome sequences, further phylogenetic analyses between E. repens and other Triticeae species revealed that E. repens, Connorochloa tenuis and three Elymus species formed a distinct clade, showing closer relationships.

The complete chloroplast genome of Dendrobium comatum (Orchidaceae)

Dendrobium comatum is a rare orchid plant. To further its research and conservation, we reported and characterized its complete chloroplast (cp) genome by using Illumina paired-end sequencing data. We also analyzed its characteristics and studied its clustering relationships. The total chloroplast genome size was 158,008 bp, including inverted repeats (IRs) of 27,032 bp separated by a large single copy (LSC) region and a small single copy (SSC) region of 85,592 and 18,352 bp, respectively. A total of 132 genes, including 38 tRNA, 8 rRNA, and 87 protein-coding genes, were identified. Phylogenetic analysis showed that D. comatum is sister to D. kingianum with sufficient support.