scholarly journals Genes Translocated into the Plastid Inverted Repeat Show Decelerated Substitution Rates and Elevated GC Content

2016 ◽  
Vol 8 (8) ◽  
pp. 2452-2458 ◽  
Author(s):  
Fay-Wei Li ◽  
Li-Yaung Kuo ◽  
Kathleen M. Pryer ◽  
Carl J. Rothfels
Keyword(s):  
Inverted Repeat ◽  
Gc Content ◽  
Substitution Rates

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

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yan-Yan Guo ◽  
Jia-Xing Yang ◽  
Ming-Zhu Bai ◽  
Guo-Qiang Zhang ◽  
Zhong-Jian Liu
Keyword(s):  
Gene Order ◽  
Inverted Repeat ◽  
Single Copy ◽  
Gene Content ◽  
Comparative Genomic ◽  
Substitution Rates ◽  
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. 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.

scholarly journals Evolutionary dynamics of the plastid inverted repeat: the effects of expansion, contraction, and loss on substitution rates

2015 ◽  
Vol 209 (4) ◽  
pp. 1747-1756 ◽  
Author(s):  
Andan Zhu ◽  
Wenhu Guo ◽  
Sakshi Gupta ◽  
Weishu Fan ◽  
Jeffrey P. Mower
Keyword(s):  
Inverted Repeat ◽  
Evolutionary Dynamics ◽  
Substitution Rates

scholarly journals Complete Chloroplast Genome of Paphiopedilum delenatii and Phylogenetic Relationships among Orchidaceae

Plants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 61 ◽  
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.

scholarly journals Complete Chloroplast Genome Sequence of Justicia flava: Genome Comparative Analysis and Phylogenetic Relationships among Acanthaceae

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Samaila S. Yaradua ◽  
Dhafer A. Alzahrani ◽  
Enas J. Albokhary ◽  
Abidina Abba ◽  
Abubakar Bello
Keyword(s):  
Comparative Analysis ◽  
Chloroplast Genome ◽  
Phylogenetic Relationships ◽  
Inverted Repeat ◽  
Gc Content ◽  
Single Copy ◽  
Protein Coding ◽  
Complete Chloroplast Genome ◽  
Protein Coding Genes ◽  
Cp Genome

The complete chloroplast genome of J. flava, an endangered medicinal plant in Saudi Arabia, was sequenced and compared with cp genome of three Acanthaceae species to characterize the cp genome, identify SSRs, and also detect variation among the cp genomes of the sampled Acanthaceae. NOVOPlasty was used to assemble the complete chloroplast genome from the whole genome data. The cp genome of J. flava was 150, 888bp in length with GC content of 38.2%, and has a quadripartite structure; the genome harbors one pair of inverted repeat (IRa and IRb 25, 500bp each) separated by large single copy (LSC, 82, 995 bp) and small single copy (SSC, 16, 893 bp). There are 132 genes in the genome, which includes 80 protein coding genes, 30 tRNA, and 4 rRNA; 113 are unique while the remaining 19 are duplicated in IR regions. The repeat analysis indicates that the genome contained all types of repeats with palindromic occurring more frequently; the analysis also identified total number of 98 simple sequence repeats (SSR) of which majority are mononucleotides A/T and are found in the intergenic spacer. The comparative analysis with other cp genomes sampled indicated that the inverted repeat regions are conserved than the single copy regions and the noncoding regions show high rate of variation than the coding region. All the genomes have ndhF and ycf1 genes in the border junction of IRb and SSC. Sequence divergence analysis of the protein coding genes showed that seven genes (petB, atpF, psaI, rpl32, rpl16, ycf1, and clpP) are under positive selection. The phylogenetic analysis revealed that Justiceae is sister to Ruellieae. This study reported the first cp genome of the largest genus in Acanthaceae and provided resources for studying genetic diversity of J. flava as well as resolving phylogenetic relationships within the core Acanthaceae.

scholarly journals Runaway GC Evolution in Gerbil Genomes

2020 ◽  
Vol 37 (8) ◽  
pp. 2197-2210 ◽  
Author(s):  
Rodrigo Pracana ◽  
Adam D Hargreaves ◽  
John F Mulley ◽  
Peter W H Holland
Keyword(s):  
Rapid Evolution ◽  
Gc Content ◽  
Synonymous Substitution ◽  
Genomic Region ◽  
Recombination Rates ◽  
Substitution Pattern ◽  
Substitution Rates ◽  
Protein Coding ◽  
Murine Rodents ◽  
Genomic Regions

Abstract Recombination increases the local GC-content in genomic regions through GC-biased gene conversion (gBGC). The recent discovery of a large genomic region with extreme GC-content in the fat sand rat Psammomys obesus provides a model to study the effects of gBGC on chromosome evolution. Here, we compare the GC-content and GC-to-AT substitution patterns across protein-coding genes of four gerbil species and two murine rodents (mouse and rat). We find that the known high-GC region is present in all the gerbils, and is characterized by high substitution rates for all mutational categories (AT-to-GC, GC-to-AT, and GC-conservative) both at synonymous and nonsynonymous sites. A higher AT-to-GC than GC-to-AT rate is consistent with the high GC-content. Additionally, we find more than 300 genes outside the known region with outlying values of AT-to-GC synonymous substitution rates in gerbils. Of these, over 30% are organized into at least 17 large clusters observable at the megabase-scale. The unusual GC-skewed substitution pattern suggests the evolution of genomic regions with very high recombination rates in the gerbil lineage, which can lead to a runaway increase in GC-content. Our results imply that rapid evolution of GC-content is possible in mammals, with gerbil species providing a powerful model to study the mechanisms of gBGC.

Rates of Nucleotide Substitution and Mammalian Nuclear Gene Evolution: Approximate and Maximum-Likelihood Methods Lead to Different Conclusions

Genetics ◽  
2000 ◽  
Vol 156 (3) ◽  
pp. 1299-1308 ◽  
Author(s):  
Joseph P Bielawski ◽  
Katherine A Dunn ◽  
Ziheng Yang
Keyword(s):  
Maximum Likelihood ◽  
Gc Content ◽  
Synonymous Substitution ◽  
Likelihood Methods ◽  
Approximate Methods ◽  
Substitution Rates ◽  
The Third ◽  
Maximum Likelihood Methods ◽  
Codon Positions ◽  
Synonymous Substitution Rates

Abstract Rates and patterns of synonymous and nonsynonymous substitutions have important implications for the origin and maintenance of mammalian isochores and the effectiveness of selection at synonymous sites. Previous studies of mammalian nuclear genes largely employed approximate methods to estimate rates of nonsynonymous and synonymous substitutions. Because these methods did not account for major features of DNA sequence evolution such as transition/transversion rate bias and unequal codon usage, they might not have produced reliable results. To evaluate the impact of the estimation method, we analyzed a sample of 82 nuclear genes from the mammalian orders Artiodactyla, Primates, and Rodentia using both approximate and maximum-likelihood methods. Maximum-likelihood analysis indicated that synonymous substitution rates were positively correlated with GC content at the third codon positions, but independent of nonsynonymous substitution rates. Approximate methods, however, indicated that synonymous substitution rates were independent of GC content at the third codon positions, but were positively correlated with nonsynonymous rates. Failure to properly account for transition/transversion rate bias and unequal codon usage appears to have caused substantial biases in approximate estimates of substitution rates.

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

Plants ◽  
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.

scholarly journals Comparative Mitogenomic Analysis and the Evolution of Rhizoctonia solani Anastomosis Groups

2021 ◽  
Vol 12 ◽  
Author(s):  
Runmao Lin ◽  
Yuan Xia ◽  
Yao Liu ◽  
Danhua Zhang ◽  
Xing Xiang ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Rhizoctonia Solani ◽  
Fungal Pathogens ◽  
Expression Patterns ◽  
Gc Content ◽  
Complete Sequence ◽  
Substitution Rates ◽  
Anastomosis Groups ◽  
Cell Functions ◽  
Host Infection

Mitochondria are the major energy source for cell functions. However, for the plant fungal pathogens, mitogenome variations and their roles during the host infection processes remain largely unknown. Rhizoctonia solani, an important soil-borne pathogen, forms different anastomosis groups (AGs) and adapts to a broad range of hosts in nature. Here, we reported three complete mitogenomes of AG1-IA RSIA1, AG1-IB RSIB1, and AG1-IC, and performed a comparative analysis with nine published Rhizoctonia mitogenomes (AG1-IA XN, AG1-IB 7/3/14, AG3, AG4, and five Rhizoctonia sp. mitogenomes). These mitogenomes encoded 15 typical proteins (cox1-3, cob, atp6, atp8-9, nad1-6, nad4L, and rps3) and several LAGLIDADG/GIY-YIG endonucleases with sizes ranging from 109,017 bp (Rhizoctonia sp. SM) to 235,849 bp (AG3). We found that their large sizes were mainly contributed by repeat sequences and genes encoding endonucleases. We identified the complete sequence of the rps3 gene in 10 Rhizoctonia mitogenomes, which contained 14 positively selected sites. Moreover, we inferred a robust maximum-likelihood phylogeny of 32 Basidiomycota mitogenomes, representing that seven R. solani and other five Rhizoctonia sp. lineages formed two parallel branches in Agaricomycotina. The comparative analysis showed that mitogenomes of Basidiomycota pathogens had high GC content and mitogenomes of R. solani had high repeat content. Compared to other strains, the AG1-IC strain had low substitution rates, which may affect its mitochondrial phylogenetic placement in the R. solani clade. Additionally, with the published RNA-seq data, we investigated gene expression patterns from different AGs during host infection stages. The expressed genes from AG1-IA (host: rice) and AG3 (host: potato) mainly formed four groups by k-mean partitioning analysis. However, conserved genes represented varied expression patterns, and only the patterns of rps3-nad2 and nad1-m3g18/mag28 (an LAGLIDADG endonuclease) were conserved in AG1-IA and AG3 as shown by the correlation coefficient analysis, suggesting regulation of gene repertoires adapting to infect varied hosts. The results of variations in mitogenome characteristics and the gene substitution rates and expression patterns may provide insights into the evolution of R. solani mitogenomes.

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