scholarly journals Complete Chloroplast Genome of Calligonum Mongolicum: Genome Organization, Codon Usage Pattern, Phylogenetic Relationships, Comparative Structure and Adaptive Evolution Analysis

2020 ◽  
Author(s):  
Huirong Duan ◽  
Qian Zhang ◽  
Hongshan Yang ◽  
Fuping Tian ◽  
Yu Hu ◽  
...  

Abstract Background The perennial shrub of Calligonum mongolicum is a dominant native plant in all Calligonum species, which has the largest and most widespread geographic distribution in arid deserts of northern China. Understanding the phylogenetic relationship between C. mongolicum and closely related plant species will offer guidance on the classification and identification of inter-species and their varieties. The chloroplast (cp) genome is an optimal model to decipher phylogenetic relationships and genome evolution in related plant families. In the present study, the complete cp genome of C. mongolicum was sequenced, and the characteristics were described, then the genomic structure was compared to other three Polygonaceae species.Results The cp genome of C. mongolicum was 162,124 bp in length with a quadripartite structure. A total of 131 functional genes were annotated, 14 different genes of which harbored introns and exons, 50 long repeat sequences and 244 simple sequences repeats were identified. Synonymous codon usage (SCU) analysis exhibited A/T preference, and 7 codons were identified as the optimal codons. Multivariate statistical analysis of parity rule 2, ENC-plot, and neutrality plot were combined conducted to imply natural selection as the crucial constraint in SCU bias in C. mongolicum cp genome.The phylogenetic tree showed that Rumex acetosa was the most related plant to C. mongolicum. From the comparative analysis of genomic structures, the inverted repeat regions (IRa and IRb) were less divergent than other parts and coding regions was relatively conserved than non-coding regions. Compared to other species in the Polygonaceae, the borders of IRb/SSC and SSC/IRa in C. mongolicum changed greatly. Furthermore, adaptive evolution analysis of 75 orthologous protein-coding genes indicated that only the psbK gene was under positive selection, which might be crucial in the adaptive evolution of C. mongolicum.Conclusions Our results comprehensively depicts the architecture of C. mongolicum cp genome, and will lay a vigorous foundation for further study on molecular marker selection, phylogenetic analysis, and population researches in Calligonum species.

2020 ◽  
Author(s):  
Hui-rong Duan ◽  
Qian Zhang ◽  
Hongshan Yang ◽  
Fuping Tian ◽  
Yu Hu ◽  
...  

Abstract BackgroundThe perennial shrub of Calligonum mongolicum is a dominant native plant in all Calligonum species, which has the largest and most widespread geographic distribution in arid deserts of northern China. Understanding the phylogenetic relationship between C. mongolicum and closely related plant species will offer guidance on the classification and identification of inter-species and their varieties. The chloroplast (cp) genome is an optimal model to decipher phylogenetic relationships and genome evolution in related plant families. In the present study, the complete cp genome of C. mongolicum was sequenced, and the characteristics were described, then the genomic structure was compared to other three Polygonaceae species.ResultsThe cp genome of C. mongolicum was 162,124 bp in length with a quadripartite structure. A total of 131 functional genes were annotated, 14 different genes of which harbored introns and exons, 50 long repeat sequences and 244 simple sequences repeats were identified. Synonymous codon usage (SCU) analysis exhibited A/T preference, and 7 codons were identified as the optimal codons. Multivariate statistical analysis of parity rule 2, ENC-plot, and neutrality plot were combined conducted to imply natural selection as the crucial constraint in SCU bias in C. mongolicum cp genome.The phylogenetic tree showed that Rumex acetosa was the most related plant to C. mongolicum. From the comparative analysis of genomic structures, the inverted repeat regions (IRa and IRb) were less divergent than other parts and coding regions was relatively conserved than non-coding regions. Compared to other species in the Polygonaceae, the borders of IRb/SSC and SSC/IRa in C. mongolicum changed greatly. Furthermore, adaptive evolution analysis of 75 orthologous protein-coding genes indicated that only the psbK gene was under positive selection, which might be crucial in the adaptive evolution of C. mongolicum.ConclusionsOur results comprehensively depicts the architecture of C. mongolicum cp genome, and will lay a vigorous foundation for further study on molecular marker selection, phylogenetic analysis, and population researches in Calligonum species.


PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261196
Author(s):  
Guangxin Cui ◽  
Chunmei Wang ◽  
Xiaoxing Wei ◽  
Hongbo Wang ◽  
Xiaoli Wang ◽  
...  

Background Hordeum brevisubulatum, known as fine perennial forage, is used for soil salinity improvement in northern China. Chloroplast (cp) genome is an ideal model for assessing its genome evolution and the phylogenetic relationships. We de novo sequenced and analyzed the cp genome of H. brevisubulatum, providing a fundamental reference for further studies in genetics and molecular breeding. Results The cp genome of H. brevisubulatum was 137,155 bp in length with a typical quadripartite structure. A total of 130 functional genes were annotated and the gene of accD was lost in the process of evolution. Among all the annotated genes, 16 different genes harbored introns and the genes of ycf3 and rps12 contained two introns. Parity rule 2 (PR2) plot analysis showed that majority of genes had a bias toward T over A in the coding strand in all five Hordeum species, and a slight G over C in the other four Hordeum species except for H. bogdanil. Additionally, 52 dispersed repeat sequences and 182 simple sequence repeats were identified. Moreover, some unique SSRs of each species could be used as molecular markers for further study. Compared to the other four Hordeum species, H. brevisubulatum was most closely related to H. bogdanii and its cp genome was relatively conserved. Moreover, inverted repeat regions (IRa and IRb) were less divergent than other parts and coding regions were relatively conserved compared to non-coding regions. Main divergence was presented at the SSC/IR border. Conclusions This research comprehensively describes the architecture of the H. brevisubulatum cp genome and improves our understanding of its cp biology and genetic diversity, which will facilitate biological discoveries and cp genome engineering.


PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10787
Author(s):  
Huirong Duan ◽  
Qian Zhang ◽  
Chunmei Wang ◽  
Fang Li ◽  
Fuping Tian ◽  
...  

Background Codon usage bias analysis is a suitable strategy for identifying the principal evolutionary driving forces in different organisms. Delphinium grandiflorum L. is a perennial herb with high economic value and typical biological characteristics. Evolutionary analysis of D. grandiflorum can provide a rich resource of genetic information for developing hybridization resources of the genus Delphinium. Methods Synonymous codon usage (SCU) and related indices of 51 coding sequences from the D. grandiflorum chloroplast (cp) genome were calculated using Codon W, Cups of EMBOSS, SPSS and Microsoft Excel. Multivariate statistical analysis combined by principal component analysis (PCA), correspondence analysis (COA), PR2-plot mapping analysis and ENC plot analysis was then conducted to explore the factors affecting the usage of synonymous codons. Results The SCU bias of D. grandiflorum was weak and codons preferred A/T ending. A SCU imbalance between A/T and G/C at the third base position was revealed by PR2-plot mapping analysis. A total of eight codons were identified as the optimal codons. The PCA and COA results indicated that base composition (GC content, GC3 content) and gene expression were important for SCU bias. A majority of genes were distributed below the expected curve from the ENC plot analysis and up the standard curve by neutrality plot analysis. Our results showed that with the exception of notable mutation pressure effects, the majority of genetic evolution in the D. grandiflorum cp genome might be driven by natural selection. Discussions Our results provide a theoretical foundation for elucidating the genetic architecture and mechanisms of D. grandiflorum, and contribute to enriching D. grandiflorum genetic resources.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhongyu Du ◽  
Ke Lu ◽  
Kai Zhang ◽  
Yiming He ◽  
Haitao Wang ◽  
...  

Abstract Background Limited access to genetic information has greatly hindered our understanding of the molecular evolution, phylogeny, and differentiation time of subg. Amygdalus. This study reported complete chloroplast (cp) genome sequences of subg. Amygdalus, which further enriched the available valuable resources of complete cp genomes of higher plants and deepened our understanding of the divergence time and phylogenetic relationships of subg. Amygdalus. Results The results showed that subg. Amygdalus species exhibited a tetrad structure with sizes ranging from 157,736 bp (P. kansuensis) to 158,971 bp (P. davidiana), a pair of inverted repeat regions (IRa/IRb) that ranged from 26,137–26,467 bp, a large single-copy region that ranged from 85,757–86,608 bp, and a small single-copy region that ranged from 19,020–19,133 bp. The average GC content of the complete cp genomes in the 12 species was 36.80%. We found that the structure of the subg. Amygdalus complete cp genomes was highly conserved, and the 12 subg. Amygdalus species had an rps19 pseudogene. There was not rearrangement of the complete cp genome in the 12 subg. Amygdalus species. All 12 subg. Amygdalus species clustered into one clade based on both Bayesian inference and maximum likelihood. The divergence time analyses based on the complete cp genome sequences showed that subg. Amygdalus species diverged approximately 15.65 Mya. Conclusion Our results provide data on the genomic structure of subg. Amygdalus and elucidates their phylogenetic relationships and divergence time.


Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1169
Author(s):  
Xin Li ◽  
Xiaocen Wang ◽  
Pengtao Gong ◽  
Nan Zhang ◽  
Xichen Zhang ◽  
...  

Giardia duodenalis, a flagellated parasitic protozoan, the most common cause of parasite-induced diarrheal diseases worldwide. Codon usage bias (CUB) is an important evolutionary character in most species. However, G. duodenalis CUB remains unclear. Thus, this study analyzes codon usage patterns to assess the restriction factors and obtain useful information in shaping G. duodenalis CUB. The neutrality analysis result indicates that G. duodenalis has a wide GC3 distribution, which significantly correlates with GC12. ENC-plot result—suggesting that most genes were close to the expected curve with only a few strayed away points. This indicates that mutational pressure and natural selection played an important role in the development of CUB. The Parity Rule 2 plot (PR2) result demonstrates that the usage of GC and AT was out of proportion. Interestingly, we identified 26 optimal codons in the G. duodenalis genome, ending with G or C. In addition, GC content, gene expression, and protein size also influence G. duodenalis CUB formation. This study systematically analyzes G. duodenalis codon usage pattern and clarifies the mechanisms of G. duodenalis CUB. These results will be very useful to identify new genes, molecular genetic manipulation, and study of G. duodenalis evolution.


2013 ◽  
Vol 100 (5) ◽  
pp. 916-929 ◽  
Author(s):  
D. E. Soltis ◽  
M. E. Mort ◽  
M. Latvis ◽  
E. V. Mavrodiev ◽  
B. C. O'Meara ◽  
...  

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2982 ◽  
Author(s):  
Mun Hua Tan ◽  
Han Ming Gan ◽  
Yin Peng Lee ◽  
Gary C.B. Poore ◽  
Christopher M. Austin

BackgroundWhole mitochondrial DNA is being increasingly utilized for comparative genomic and phylogenetic studies at deep and shallow evolutionary levels for a range of taxonomic groups. Although mitogenome sequences are deposited at an increasing rate into public databases, their taxonomic representation is unequal across major taxonomic groups. In the case of decapod crustaceans, several infraorders, including Axiidea (ghost shrimps, sponge shrimps, and mud lobsters) and Caridea (true shrimps) are still under-represented, limiting comprehensive phylogenetic studies that utilize mitogenomic information.MethodsSequence reads from partial genome scans were generated using the Illumina MiSeq platform and mitogenome sequences were assembled from these low coverage reads. In addition to examining phylogenetic relationships within the three infraorders, Axiidea, Gebiidea, and Caridea, we also investigated the diversity and frequency of codon usage bias and mitogenome gene order rearrangements.ResultsWe present new mitogenome sequences for five shrimp species from Australia that includes two ghost shrimps,Callianassa ceramicaandTrypaea australiensis, along with three caridean shrimps,Macrobrachium bullatum,Alpheus lobidens, andCaridinacf.nilotica. Strong differences in codon usage were discovered among the three infraorders and significant gene order rearrangements were observed. While the gene order rearrangements are congruent with the inferred phylogenetic relationships and consistent with taxonomic classification, they are unevenly distributed within and among the three infraorders.DiscussionOur findings suggest potential for mitogenome rearrangements to be useful phylogenetic markers for decapod crustaceans and at the same time raise important questions concerning the drivers of mitogenome evolution in different decapod crustacean lineages.


2021 ◽  
pp. 1450-1458
Author(s):  
Sharanagouda S. Patil ◽  
Uma Bharathi Indrabalan ◽  
Kuralayanapalya Puttahonnappa Suresh ◽  
Bibek Ranjan Shome

Background and Aim: Classical swine fever (CSF), caused by CSF virus (CSFV), is a highly contagious disease in pigs causing 100% mortality in susceptible adult pigs and piglets. High mortality rate in pigs causes huge economic loss to pig farmers. CSFV has a positive-sense RNA genome of 12.3 kb in length flanked by untranslated regions at 5' and 3' end. The genome codes for a large polyprotein of 3900 amino acids coding for 11 viral proteins. The 1300 codons in the polyprotein are coded by different combinations of three nucleotides which help the infectious agent to evolve itself and adapt to the host environment. This study performed and employed various methods/techniques to estimate the changes occurring in the process of CSFV evolution by analyzing the codon usage pattern. Materials and Methods: The evolution of viruses is widely studied by analyzing their nucleotides and coding regions/ codons using various methods. A total of 115 complete coding regions of CSFVs including one complete genome from our laboratory (MH734359) were included in this study and analysis was carried out using various methods in estimating codon usage bias and evolution. This study elaborates on the factors that influence the codon usage pattern. Results: The effective number of codons (ENC) and relative synonymous codon usage showed the presence of codon usage bias. The mononucleotide (A) has a higher frequency compared to the other mononucleotides (G, C, and T). The dinucleotides CG and CC are underrepresented and overrepresented. The codons CGT was underrepresented and AGG was overrepresented. The codon adaptation index value of 0.71 was obtained indicating that there is a similarity in the codon usage bias. The principal component analysis, ENC-plot, Neutrality plot, and Parity Rule 2 plot produced in this article indicate that the CSFV is influenced by the codon usage bias. The mutational pressure and natural selection are the important factors that influence the codon usage bias. Conclusion: The study provides useful information on the codon usage analysis of CSFV and may be utilized to understand the host adaptation to virus environment and its evolution. Further, such findings help in new gene discovery, design of primers/probes, design of transgenes, determination of the origin of species, prediction of gene expression level, and gene function of CSFV. To the best of our knowledge, this is the first study on codon usage bias involving such a large number of complete CSFVs including one sequence of CSFV from India.


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