The chloroplast genome evolution of Venus slipper (Paphiopedilum): IR expansion, SSC contraction, and highly rearranged SSC regions

Abstract Background Paphiopedilum is the largest genus of slipper orchids. Previous studies showed that the phylogenetic relationships of this genus are not well resolved, and sparse taxon sampling documented inverted repeat (IR) expansion and small single copy (SSC) contraction of the chloroplast genomes of Paphiopedilum. Results Here, we sequenced, assembled, and annotated 77 plastomes of Paphiopedilum species (size range of 152,130 – 164,092 bp). The phylogeny based on the plastome resolved the relationships of the genus except for the phylogenetic position of two unstable species. We used phylogenetic and comparative genomic approaches to elucidate the plastome evolution of Paphiopedilum. The plastomes of Paphiopedilum have a conserved genome structure and gene content except in the SSC region. The large single copy/inverted repeat (LSC/IR) boundaries are relatively stable, while the boundaries of the inverted repeat and small single copy region (IR/SSC) varied among species. Corresponding to the IR/SSC boundary shifts, the chloroplast genomes of the genus experienced IR expansion and SSC contraction. The IR region incorporated one to six genes of the SSC region. Unexpectedly, great variation in the size, gene order, and gene content of the SSC regions was found, especially in the subg. Parvisepalum. Furthermore, Paphiopedilum provides evidence for the ongoing degradation of the ndh genes in the photoautotrophic plants. The estimated substitution rates of the protein coding genes show accelerated rates of evolution in clpP, psbH, and psbZ. Genes transferred to the IR region due to the boundary shift also have higher substitution rates. Conclusions We found IR expansion and SSC contraction in the chloroplast genomes of Paphiopedilum with dense sampling, and the genus shows variation in the size, gene order, and gene content of the SSC region. This genus provides an ideal system to investigate the dynamics of plastome evolution.

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The Chloroplast Genome Evolution of Venus Slipper (Paphiopedilum): IR Expansion, SSC Contraction, and Highly Rearranged SSC Regions

10.21203/rs.3.rs-257472/v1 ◽

2021 ◽

Author(s):

Yan-Yan Guo ◽

Jia-Xing Yang ◽

Guo-Qiang Zhang ◽

Zhong-Jian Liu

Keyword(s):

Gene Order ◽

Inverted Repeat ◽

Genome Structure ◽

Single Copy ◽

Gene Content ◽

Comparative Genomic ◽

Plastome Evolution ◽

Chloroplast Genomes ◽

Ideal System ◽

Small Single Copy

Abstract Background: Paphiopedilum is the largest genus of slipper orchids. Previous studies showed that the phylogenetic relationships of this genus are not well resolved, and sparse taxon sampling documented inverted repeat (IR) expansion and small single copy (SSC) contraction of the chloroplast genomes of Paphiopedilum. Here, we sequenced, assembled, and annotated 77 plastomes of Paphiopedilum species. The phylogeny based on the plastome resolved the relationships of the genus except for the phylogenetic position of two unstable species. We used phylogenetic and comparative genomic approaches to elucidate the plastome evolution of Paphiopedilum.Results: The plastomes of Paphiopedilum have conserved genome structure and gene content except in the SSC region. The large single copy/inverted repeat (LSC/IR) boundaries are relatively stable, while the boundaries of inverted repeat/small single copy (IR/SSC) boundaries varied among species. Corresponding to the IR/SSC boundary shifts, the chloroplast genomes of the genus experienced IR expansion and SSC contraction. The IR region incorporated one to six genes of the SSC region. Unexpectedly, great variation in the size, gene order, and gene content of the SSC regions was found, especially in the subg. Parvisepalum. Furthermore, Paphiopedilum provides evidence for the ongoing degradation of the ndh genes in the photoautotrophic plants. The estimated substitution rates of the protein coding genes show accelerated rates of evolution in clpP, psbH, and psbZ. Genes transferred to the IR region due to the boundary shift also have higher substitution rates.Conclusions: We found IR expansion and SSC contraction in the chloroplast genomes of Paphiopedilum with dense sampling, and the genus shows variation in the size, gene order, and gene content of the SSC region. This genus provides an ideal system to investigate the dynamics of plastome evolution.

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Two Korean Endemic Clematis Chloroplast Genomes: Inversion, Reposition, Expansion of the Inverted Repeat Region, Phylogenetic Analysis, and Nucleotide Substitution Rates

Plants ◽

10.3390/plants10020397 ◽

2021 ◽

Vol 10 (2) ◽

pp. 397

Author(s):

Kyoung Su Choi ◽

Young-Ho Ha ◽

Hee-Young Gil ◽

Kyung Choi ◽

Dong-Kap Kim ◽

...

Keyword(s):

Phylogenetic Analysis ◽

Inverted Repeat ◽

Nonsynonymous Substitution ◽

Single Copy ◽

Inverted Repeat Region ◽

Substitution Rates ◽

Protein Coding ◽

Protein Coding Genes ◽

Chloroplast Genomes ◽

Fundamental Information

Previous studies on the chloroplast genome in Clematis focused on the chloroplast structure within Anemoneae. The chloroplast genomes of Cleamtis were sequenced to provide information for studies on phylogeny and evolution. Two Korean endemic Clematis chloroplast genomes (Clematis brachyura and C. trichotoma) range from 159,170 to 159,532 bp, containing 134 identical genes. Comparing the coding and non-coding regions among 12 Clematis species revealed divergent sites, with carination occurring in the petD-rpoA region. Comparing other Clematis chloroplast genomes suggested that Clematis has two inversions (trnH-rps16 and rps4), reposition (trnL-ndhC), and inverted repeat (IR) region expansion. For phylogenetic analysis, 71 protein-coding genes were aligned from 36 Ranunculaceae chloroplast genomes. Anemoneae (Anemoclema, Pulsatilla, Anemone, and Clematis) clades were monophyletic and well-supported by the bootstrap value (100%). Based on 70 chloroplast protein-coding genes, we compared nonsynonymous (dN) and synonymous (dS) substitution rates among Clematis, Anemoneae (excluding Clematis), and other Ranunculaceae species. The average synonymoussubstitution rates (dS)of large single copy (LSC), small single copy (SSC), and IR genes in Anemoneae and Clematis were significantly higher than those of other Ranunculaceae species, but not the nonsynonymous substitution rates (dN). This study provides fundamental information on plastid genome evolution in the Ranunculaceae.

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A Circular Chloroplast Genome of Fagus sylvatica Reveals High Conservation between Two Individuals from Germany and One Individual from Poland and an Alternate Direction of the Small Single-Copy Region

Forests ◽

10.3390/f12020180 ◽

2021 ◽

Vol 12 (2) ◽

pp. 180

Author(s):

Bagdevi Mishra ◽

Bartosz Ulaszewski ◽

Sebastian Ploch ◽

Jaroslaw Burczyk ◽

Marco Thines

Keyword(s):

Chloroplast Genome ◽

Fagus Sylvatica ◽

Pollen Dispersal ◽

European Beech ◽

Single Copy ◽

Migration History ◽

Chloroplast Genomes ◽

Long Read ◽

The Individual ◽

Small Single Copy

Chloroplasts are difficult to assemble because of the presence of large inverted repeats. At the same time, correct assemblies are important, as chloroplast loci are frequently used for biogeography and population genetics studies. In an attempt to elucidate the orientation of the single-copy regions and to find suitable loci for chloroplast single nucleotide polymorphism (SNP)-based studies, circular chloroplast sequences for the ultra-centenary reference individual of European Beech (Fagus sylvatica), Bhaga, and an additional Polish individual (named Jamy) was obtained based on hybrid assemblies. The chloroplast genome of Bhaga was 158,458 bp, and that of Jamy was 158,462 bp long. Using long-read mapping on the configuration inferred in this study and the one suggested in a previous study, we found an inverted orientation of the small single-copy region. The chloroplast genome of Bhaga and of the individual from Poland both have only two mismatches as well as three and two indels as compared to the previously published genome, respectively. The low divergence suggests low seed dispersal but high pollen dispersal. However, once chloroplast genomes become available from Pleistocene refugia, where a high degree of variation has been reported, they might prove useful for tracing the migration history of Fagus sylvatica in the Holocene.

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Extensive genomic rearrangements mediated by repetitive sequences in plastomes of Medicago and its relatives

BMC Plant Biology ◽

10.1186/s12870-021-03202-3 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Shuang Wu ◽

Jinyuan Chen ◽

Ying Li ◽

Ai Liu ◽

Ao Li ◽

...

Keyword(s):

Tandem Repeats ◽

Genome Instability ◽

Repetitive Sequences ◽

Genomic Analysis ◽

Genomic Rearrangements ◽

Comparative Genomic ◽

Length Variation ◽

Substitution Rates ◽

Repeat Content ◽

Plastome Evolution

Abstract Background Although plastomes are highly conserved with respect to gene content and order in most photosynthetic angiosperms, extensive genomic rearrangements have been reported in Fabaceae, particularly within the inverted repeat lacking clade (IRLC) of Papilionoideae. Two hypotheses, i.e., the absence of the IR and the increased repeat content, have been proposed to affect the stability of plastomes. However, this is still unclear for the IRLC species. Here, we aimed to investigate the relationships between repeat content and the degree of genomic rearrangements in plastomes of Medicago and its relatives Trigonella and Melilotus, which are nested firmly within the IRLC. Results We detected abundant repetitive elements and extensive genomic rearrangements in the 75 newly assembled plastomes of 20 species, including gene loss, intron loss and gain, pseudogenization, tRNA duplication, inversion, and a second independent IR gain (IR ~ 15 kb in Melilotus dentata) in addition to the previous first reported cases in Medicago minima. We also conducted comparative genomic analysis to evaluate plastome evolution. Our results indicated that the overall repeat content is positively correlated with the degree of genomic rearrangements. Some of the genomic rearrangements were found to be directly linked with repetitive sequences. Tandem repeated sequences have been detected in the three genes with accelerated substitution rates (i.e., accD, clpP, and ycf1) and their length variation could be explained by the insertions of tandem repeats. The repeat contents of the three localized hypermutation regions around these three genes with accelerated substitution rates are also significantly higher than that of the remaining plastome sequences. Conclusions Our results suggest that IR reemergence in the IRLC species does not ensure their plastome stability. Instead, repeat-mediated illegitimate recombination is the major mechanism leading to genome instability, a pattern in agreement with recent findings in other angiosperm lineages. The plastome data generated herein provide valuable genomic resources for further investigating the plastome evolution in legumes.

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Complete Chloroplast Genome of Paphiopedilum delenatii and Phylogenetic Relationships among Orchidaceae

Plants ◽

10.3390/plants9010061 ◽

2020 ◽

Vol 9 (1) ◽

pp. 61 ◽

Cited By ~ 5

Author(s):

Huyen-Trang Vu ◽

Ngan Tran ◽

Thanh-Diem Nguyen ◽

Quoc-Luan Vu ◽

My-Huyen Bui ◽

...

Keyword(s):

Chloroplast Genome ◽

Inverted Repeat ◽

Gc Content ◽

Single Copy ◽

Rrna Genes ◽

Trna Genes ◽

Complete Chloroplast Genome ◽

Critically Endangered Species ◽

Plastid Genomes ◽

Chloroplast Genomes

Paphiopedilum delenatii is a native orchid of Vietnam with highly attractive floral traits. Unfortunately, it is now listed as a critically endangered species with a few hundred individuals remaining in nature. In this study, we performed next-generation sequencing of P. delenatii and assembled its complete chloroplast genome. The whole chloroplast genome of P. delenatii was 160,955 bp in size, 35.6% of which was GC content, and exhibited typical quadripartite structure of plastid genomes with four distinct regions, including the large and small single-copy regions and a pair of inverted repeat regions. There were, in total, 130 genes annotated in the genome: 77 coding genes, 39 tRNA genes, 8 rRNA genes, and 6 pseudogenes. The loss of ndh genes and variation in inverted repeat (IR) boundaries as well as data of simple sequence repeats (SSRs) and divergent hotspots provided useful information for identification applications and phylogenetic studies of Paphiopedilum species. Whole chloroplast genomes could be used as an effective super barcode for species identification or for developing other identification markers, which subsequently serves the conservation of Paphiopedilum species.

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Dynamics and evolution of the inverted repeat-large single copy junctions in the chloroplast genomes of monocots

BMC Evolutionary Biology ◽

10.1186/1471-2148-8-36 ◽

2008 ◽

Vol 8 (1) ◽

pp. 36 ◽

Cited By ~ 175

Author(s):

Rui-Jiang Wang ◽

Chiao-Lei Cheng ◽

Ching-Chun Chang ◽

Chun-Lin Wu ◽

Tian-Mu Su ◽

...

Keyword(s):

Inverted Repeat ◽

Single Copy ◽

Large Single Copy ◽

Chloroplast Genomes

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Complete Chloroplast Genomes of Fagus sylvatica L. Reveal Sequence Conservation in the Inverted Repeat and the Presence of Allelic Variation in NUPTs

Genes ◽

10.3390/genes12091357 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1357

Author(s):

Bartosz Ulaszewski ◽

Joanna Meger ◽

Bagdevi Mishra ◽

Marco Thines ◽

Jarosław Burczyk

Keyword(s):

Fagus Sylvatica ◽

Inverted Repeat ◽

Allelic Variation ◽

Phylogenetic Analyses ◽

Geographic Distance ◽

European Beech ◽

Single Copy ◽

Chloroplast Genomes ◽

Efficient Suppression ◽

Broadleaved Tree Species

Growing amounts of genomic data and more efficient assembly tools advance organelle genomics at an unprecedented scale. Genomic resources are increasingly used for phylogenetic analyses of many plant species, but are less frequently used to investigate within-species variability and phylogeography. In this study, we investigated genetic diversity of Fagus sylvatica, an important broadleaved tree species of European forests, based on complete chloroplast genomes of 18 individuals sampled widely across the species distribution. Our results confirm the hypothesis of a low cpDNA diversity in European beech. The chloroplast genome size was remarkably stable (158,428 ± 37 bp). The polymorphic markers, 12 microsatellites (SSR), four SNPs and one indel, were found only in the single copy regions, while inverted repeat regions were monomorphic both in terms of length and sequence, suggesting highly efficient suppression of mutation. The within-individual analysis of polymorphisms showed >9k of markers which were proportionally present in gene and non-gene areas. However, an investigation of the frequency of alternate alleles revealed that the source of this diversity originated likely from nuclear-encoded plastome remnants (NUPTs). Phylogeographic and Mantel correlation analysis based on the complete chloroplast genomes exhibited clustering of individuals according to geographic distance in the first distance class, suggesting that the novel markers and in particular the cpSSRs could provide a more detailed picture of beech population structure in Central Europe.

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Complete chloroplast genome sequences of Dioscorea: Characterization, genomic resources, and phylogenetic analyses

PeerJ ◽

10.7717/peerj.6032 ◽

2018 ◽

Vol 6 ◽

pp. e6032 ◽

Cited By ~ 12

Author(s):

Zhenyu Zhao ◽

Xin Wang ◽

Yi Yu ◽

Subo Yuan ◽

Dan Jiang ◽

...

Keyword(s):

Chloroplast Genome ◽

Phylogenetic Analyses ◽

Single Copy ◽

Genome Sequences ◽

Complete Chloroplast Genome ◽

Genomic Resources ◽

Chloroplast Genomes ◽

The Family ◽

Small Single Copy

Dioscorea L., the largest genus of the family Dioscoreaceae with over 600 species, is not only an important food but also a medicinal plant. The identification and classification of Dioscorea L. is a rather difficult task. In this study, we sequenced five Dioscorea chloroplast genomes, and analyzed with four other chloroplast genomes of Dioscorea species from GenBank. The Dioscorea chloroplast genomes displayed the typical quadripartite structure of angiosperms, which consisted of a pair of inverted repeats separated by a large single-copy region, and a small single-copy region. The location and distribution of repeat sequences and microsatellites were determined, and the rapidly evolving chloroplast genome regions (trnK-trnQ, trnS-trnG, trnC-petN, trnE-trnT, petG-trnW-trnP, ndhF, trnL-rpl32, and ycf1) were detected. Phylogenetic relationships of Dioscorea inferred from chloroplast genomes obtained high support even in shortest internodes. Thus, chloroplast genome sequences provide potential molecular markers and genomic resources for phylogeny and species identification.

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