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1.
PLoS One ; 15(7): e0236590, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32735595

RESUMO

Zingiber montanum (Z. montanum) and Zingiber zerumbet (Z. zerumbet) are important medicinal and ornamental herbs in the genus Zingiber and family Zingiberaceae. Chloroplast-derived markers are useful for species identification and phylogenetic studies, but further development is warranted for these two Zingiber species. In this study, we report the complete chloroplast genomes of Z. montanum and Z. zerumbet, which had lengths of 164,464 bp and 163,589 bp, respectively. These genomes had typical quadripartite structures with a large single copy (LSC, 87,856-89,161 bp), a small single copy (SSC, 15,803-15,642 bp), and a pair of inverted repeats (IRa and IRb, 29,393-30,449 bp). We identified 111 unique genes in each chloroplast genome, including 79 protein-coding genes, 28 tRNAs and 4 rRNA genes. We analyzed the molecular structures, gene information, amino acid frequencies, codon usage patterns, RNA editing sites, simple sequence repeats (SSRs) and long repeats from the two chloroplast genomes. A comparison of the Z. montanum and Z. zerumbet chloroplast genomes detected 489 single-nucleotide polymorphisms (SNPs) and 172 insertions/deletions (indels). Thirteen highly divergent regions, including ycf1, rps19, rps18-rpl20, accD-psaI, psaC-ndhE, psbA-trnK-UUU, trnfM-CAU-rps14, trnE-UUC-trnT-UGU, ccsA-ndhD, psbC-trnS-UGA, start-psbA, petA-psbJ, and rbcL-accD, were identified and might be useful for future species identification and phylogeny in the genus Zingiber. Positive selection was observed for ATP synthase (atpA and atpB), RNA polymerase (rpoA), small subunit ribosomal protein (rps3) and other protein-coding genes (accD, clpP, ycf1, and ycf2) based on the Ka/Ks ratios. Additionally, chloroplast SNP-based phylogeny analyses found that Zingiber was a monophyletic sister branch to Kaempferia and that chloroplast SNPs could be used to identify Zingiber species. The genome resources in our study provide valuable information for the identification and phylogenetic analysis of the genus Zingiber and family Zingiberaceae.


Assuntos
Genoma de Cloroplastos/genética , Genômica , Filogenia , Zingiberaceae/genética , Códon/genética , Mutação INDEL , Repetições de Microssatélites/genética , Polimorfismo de Nucleotídeo Único , Edição de RNA
2.
BMC Evol Biol ; 20(1): 96, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32736519

RESUMO

BACKGROUND: Chloroplast genome sequence data is very useful in studying/addressing the phylogeny of plants at various taxonomic ranks. However, there are no empirical observations on the patterns, directions, and mutation rates, which are the key topics in chloroplast genome evolution. In this study, we used Calycanthaceae as a model to investigate the evolutionary patterns, directions and rates of both nucleotide substitutions and structural mutations at different taxonomic ranks. RESULTS: There were 2861 polymorphic nucleotide sites on the five chloroplast genomes, and 98% of polymorphic sites were biallelic. There was a single-nucleotide substitution bias in chloroplast genomes. A â†’ T or T â†’ A (2.84%) and G â†’ C or C â†’ G (3.65%) were found to occur significantly less frequently than the other four transversion mutation types. Synonymous mutations kept balanced pace with nonsynonymous mutations, whereas biased directions appeared between transition and transversion mutations and among transversion mutations. Of the structural mutations, indels and repeats had obvious directions, but microsatellites and inversions were non-directional. Structural mutations increased the single nucleotide mutations rates. The mutation rates per site per year were estimated to be 0.14-0.34 × 10- 9 for nucleotide substitution at different taxonomic ranks, 0.64 × 10- 11 for indels and 1.0 × 10- 11 for repeats. CONCLUSIONS: Our direct counts of chloroplast genome evolution events provide raw data for correctly modeling the evolution of sequence data for phylogenetic inferences.


Assuntos
Calycanthaceae/genética , Evolução Molecular , Genoma de Cloroplastos , Mutação/genética , Nucleotídeos/genética , Polimorfismo de Nucleotídeo Único/genética , Alelos , Sequência de Bases , Cloroplastos/genética , Inversão Cromossômica/genética , Loci Gênicos , Mutação INDEL/genética , Repetições de Microssatélites/genética , Taxa de Mutação , Filogenia , Especificidade da Espécie
3.
Nat Commun ; 11(1): 3670, 2020 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-32728126

RESUMO

Our understanding of polyploid genome evolution is constrained because we cannot know the exact founders of a particular polyploid. To differentiate between founder effects and post polyploidization evolution, we use a pan-genomic approach to study the allotetraploid Brachypodium hybridum and its diploid progenitors. Comparative analysis suggests that most B. hybridum whole gene presence/absence variation is part of the standing variation in its diploid progenitors. Analysis of nuclear single nucleotide variants, plastomes and k-mers associated with retrotransposons reveals two independent origins for B. hybridum, ~1.4 and ~0.14 million years ago. Examination of gene expression in the younger B. hybridum lineage reveals no bias in overall subgenome expression. Our results are consistent with a gradual accumulation of genomic changes after polyploidization and a lack of subgenome expression dominance. Significantly, if we did not use a pan-genomic approach, we would grossly overestimate the number of genomic changes attributable to post polyploidization evolution.


Assuntos
Brachypodium/genética , Diploide , Evolução Molecular , Genoma de Planta , Poliploidia , Cromossomos de Plantas/genética , Genoma de Cloroplastos , Genômica , Hibridização Genética , Filogenia , Polimorfismo de Nucleotídeo Único , Retroelementos/genética , Especificidade da Espécie
5.
PLoS One ; 15(4): e0232295, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32353023

RESUMO

In Rubiaceae phylogenetics, the number of markers often proved a limitation with authors failing to provide well-supported trees at tribal and generic levels. A robust phylogeny is a prerequisite to study the evolutionary patterns of traits at different taxonomic levels. Advances in next-generation sequencing technologies have revolutionized biology by providing, at reduced cost, huge amounts of data for an increased number of species. Due to their highly conserved structure, generally recombination-free, and mostly uniparental inheritance, chloroplast DNA sequences have long been used as choice markers for plant phylogeny reconstruction. The main objectives of this study are: 1) to gain insight in chloroplast genome evolution in the Rubiaceae (Ixoroideae) through efficient methodology for de novo assembly of plastid genomes; and, 2) to test the efficiency of mining SNPs in the nuclear genome of Ixoroideae based on the use of a coffee reference genome to produce well-supported nuclear trees. We assembled whole chloroplast genome sequences for 27 species of the Rubiaceae subfamily Ixoroideae using next-generation sequences. Analysis of the plastid genome structure reveals a relatively good conservation of gene content and order. Generally, low variation was observed between taxa in the boundary regions with the exception of the inverted repeat at both the large and short single copy junctions for some taxa. An average of 79% of the SNP determined in the Coffea genus are transferable to Ixoroideae, with variation ranging from 35% to 96%. In general, the plastid and the nuclear genome phylogenies are congruent with each other. They are well-resolved with well-supported branches. Generally, the tribes form well-identified clades but the tribe Sherbournieae is shown to be polyphyletic. The results are discussed relative to the methodology used and the chloroplast genome features in Rubiaceae and compared to previous Rubiaceae phylogenies.


Assuntos
Cloroplastos/genética , DNA de Cloroplastos/genética , Genoma de Cloroplastos/genética , Genoma de Planta/genética , Rubiaceae/genética , Coffea/genética , Evolução Molecular , Genômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Filogenia , Polimorfismo de Nucleotídeo Único/genética , Análise de Sequência de DNA/métodos
6.
Biol Res ; 53(1): 21, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32410692

RESUMO

BACKGROUND: Liriodendron chinense ranges widely in subtropical China and northern Vietnam; however, it inhabits several small, isolated populations and is now an endangered species due to its limited seed production. The objective of this study was to develop a set of nuclear SSR (simple sequence repeats) and multiple chloroplast genome markers for genetic studies in L. chinense and their characterization in diverse germplasm. RESULTS: We performed low-coverage whole genome sequencing of the L. chinense from four genotypes, assembled the chloroplast genome and identified nuclear SSR loci by searching in contigs for SSR motifs. Comparative analysis of the four chloroplast genomes of L. chinense revealed 45 SNPs, 17 indels, 49 polymorphic SSR loci, and five small inversions. Most chloroplast intraspecific polymorphisms were located in the interspaces of single-copy regions. In total, 6147 SSR markers were isolated from low-coverage whole genome sequences. The most common SSR motifs were dinucleotide (70.09%), followed by trinucleotide motifs (23.10%). The motif AG/TC (33.51%) was the most abundant, followed by TC/AG (25.53%). A set of 13 SSR primer combinations were tested for amplification and their ability to detect polymorphisms in a set of 109 L. chinense individuals, representing distinct varieties or germplasm. The number of alleles per locus ranged from 8 to 28 with an average of 21 alleles. The expected heterozygosity (He) varied from 0.19 to 0.93 and the observed heterozygosity (Ho) ranged from 0.11 to 0.79. CONCLUSIONS: The genetic resources characterized and tested in this study provide a valuable tool to detect polymorphisms in L. chinense for future genetic studies and breeding programs.


Assuntos
Genoma de Cloroplastos/genética , Genoma de Planta/genética , Liriodendron/genética , Polimorfismo Genético/genética , Alelos , Primers do DNA/genética , DNA de Plantas/genética , Genótipo , Repetições de Microssatélites , Sequenciamento Completo do Genoma
7.
BMC Evol Biol ; 20(1): 51, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32375634

RESUMO

BACKGROUND: Raw second-generation (2G) lignocellulosic biomass materials have the potential for development into a sustainable and renewable source of energy. Poplar is regarded as a promising 2G material (P. davidiana Dode×P. bolleana Lauch, P. bolleana, P. davidiana, P. euphratica, et al). However, their large-scale commercialization still faces many obstacles. For example, drought prevents sufficient irrigation or rainfall, which can reduce soil moisture and eventually destroy the chloroplast, the plant photosynthetic organelle. Heterosis is widely used in the production of drought-tolerant materials, such as the superior clone "Shanxinyang" selected from the offspring of Populus davidiana Dode×Populus bolleana Lauch. Because it produces good wood and is easily genetically transformed, "Shanxinyang" has become a promising material for use in tree genetics. It is also one of the most abundant biofuel plants in northern China. Understanding the genetic features of chloroplasts, the cp transcriptome and physiology is crucial to elucidating the chloroplast drought-response model. RESULTS: In this study, the whole genome of "Shanxinyang" was sequenced. The chloroplast genome was assembled, and chloroplast structure was analysed and compared with that of other popular plants. Chloroplast transcriptome analysis was performed under drought conditions. The total length of the "Shanxinyang" chloroplast genome was 156,190 bp, the GC content was 36.75%, and the genome was composed of four typical areas (LSC, IRa, IRb, and SSC). A total of 114 simple repeats were detected in the chloroplast genome of "Shanxinyang". In cp transcriptome analysis, we found 161 up-regulated and 157 down-regulated genes under drought, and 9 cpDEGs was randomly selected to conduct reverse transcription (RT)-qPCR., in which the Log2 (fold change) was significantly consistent with the qPCR results. The analysis of chloroplast transcription under drought provided clues for understanding chloroplast function under drought. The phylogenetic position of "Shanxinyang" within Populus was analysed by using the chloroplast genome sequences of 23 Populus plants, showing that "Shanxinyang" belongs to Sect. Populus and is sister to Populus davidiana. Further, mVISTA analysis showed that the variation in non-coding (regulatory) regions was greater than that in coding regions, which suggests that further attention should be paid to the chloroplast in order to obtain new evolutionary or functional insights related to aspects of plant biology. CONCLUSIONS: Our findings indicate that complex prokaryotic genome regulation occurs when processing transcripts under drought stress. The results not only offer clues for understanding the chloroplast genome and transcription features in woody plants but also serve as a basis for future molecular studies on poplar species.


Assuntos
Cloroplastos/genética , Secas , Filogenia , Populus/classificação , Populus/genética , Transcriptoma/genética , Composição de Bases/genética , Sequência de Bases , Éxons/genética , Regulação da Expressão Gênica de Plantas , Genoma de Cloroplastos , Íntrons/genética , Sequências Repetidas Invertidas/genética , Anotação de Sequência Molecular
8.
Sheng Wu Gong Cheng Xue Bao ; 36(4): 772-781, 2020 Apr 25.
Artigo em Chinês | MEDLINE | ID: mdl-32347071

RESUMO

Rhus chinensis is an important economic species, which could provide raw materials for pharmaceutical and industrial dyes. Rhus chinensis is famous for its resistance to drought, cold, and salt. It grows in temperate, warm temperate, and subtropical regions. We report here Rhus chinensis chloroplast genomes by de novo sequencing. The results show that the length of Rhus chinensis was 159 082 bp, exhibiting a typical four-part structure with two single-copy regions (long single copy [LSC] and short single copy [SSC] sections) separated by a pair of inverted repeats (IRs). The length of LSC and SSC was 85 394 bp and 18 663 bp, respectively. The genomes contained 126 genes, including 88 protein encoding genes, 8 rRNA and 30 tRNA genes. In the chloroplast genome, 61.97% of the sequence were gene coding region. In the sequence of gene encoding region, the vast majority of sequences were protein encoding region, accounting for 86.65%, followed by rRNA (10 620 bp, 10.77%) and tRNA (2 540 bp, 2.58%). In Rhus chinensis chloroplast genome, only 8 genes contain introns, all containing 1 intron except ycf3 gene (2 introns). The Rhus chinensis chloroplast genome contains 755 SSR locies. SSR mainly consists of dinucleotide and mononucleotide, accounting for 60% (453) and 28.74% (217) respectively. The clustering results show that Anacardiaceae were closest to Rhus chinensis, followed by Aceraceae and Sapindaceae. This study provides a molecular basis for the classification of Rhus chinensis.


Assuntos
Genoma de Cloroplastos , Rhus , Análise de Sequência de DNA , Genoma de Cloroplastos/genética , Fases de Leitura Aberta , Filogenia , Rhus/classificação , Rhus/genética
9.
Ann Bot ; 125(7): 1039-1055, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32239179

RESUMO

BACKGROUND AND AIMS: The genus Allium L., one of the largest monocotyledonous genera and one that includes many economically important crops with nutritional and medicinal value, has been the focus of classification or phylogeny studies for centuries. Recent studies suggested that the genus can be divided into 15 subgenera and 72 sections, which were further classified into three evolutionary lineages. However, the phylogenetic relationships reconstructed by one or two loci showed weaker support, especially for the third evolutionary lineage, which might not show the species relationships very clearly and could hinder further adaptive and evolutionary study. METHODS: In this study, a total of 39 complete chloroplast genomes of Allium (covering 12 Allium subgenera) were collected, and combining these with 125 species of plastomes from 19 other families of monocots, we reconstructed the phylogeny of the genus Allium, estimated the origin and divergence time of the three evolutionary lineages and investigated the adaptive evolution in this genus and related families. RESULTS: Our phylogenetic analysis confirmed the monophyly and three evolutionary lineages of Allium, while new species relationships were detected within the third evolutionary lineage. The divergence time of the three evolutionary lineages was estimated to be in the early Eocene to the middle Miocene, and numerous positive selected genes (PSGs) and PSGs with high average Ka/Ks values were found in Allium species. CONCLUSIONS: Our results detected a well-supported phylogenetic relationship of Allium. The PSGs and PSGs with high Ka/Ks values, as well as diversified morphologies, complicated chromosome characteristics and unique reproductive modes may play important roles in the adaptation and evolution of Allium species. This is the first study that conducted phylogenetic and evolutionary analyses on the genus Allium combined with the plastome and morphological and cytological data. We hope that this study can contribute to further analysis of Allium for other researchers.


Assuntos
Allium/genética , Amaryllidaceae , Genoma de Cloroplastos , Evolução Molecular , Filogenia , Análise de Sequência de DNA
10.
BMC Bioinformatics ; 21(Suppl 2): 83, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32164552

RESUMO

BACKGROUND: Previously, a seven-cluster pattern claiming to be a universal one in bacterial genomes has been reported. Keeping in mind the most popular theory of chloroplast origin, we checked whether a similar pattern is observed in chloroplast genomes. RESULTS: Surprisingly, eight cluster structure has been found, for chloroplasts. The pattern observed for chloroplasts differs rather significantly, from bacterial one, and from that latter observed for cyanobacteria. The structure is provided by clustering of the fragments of equal length isolated within a genome so that each fragment is converted in triplet frequency dictionary with non-overlapping triplets with no gaps in frame tiling. The points in 63-dimensional space were clustered due to elastic map technique. The eight cluster found in chloroplasts comprises the fragments of a genome bearing tRNA genes and exhibiting excessively high GC-content, in comparison to the entire genome. CONCLUSION: Chloroplasts exhibit very specific symmetry type in distribution of coding and non-coding fragments of a genome in the space of triplet frequencies: this is mirror symmetry. Cyanobacteria may have both mirror symmetry, and the rotational symmetry typical for other bacteria.


Assuntos
Cloroplastos/genética , Genoma de Cloroplastos , Composição de Bases , Análise por Conglomerados , Cianobactérias/genética , RNA de Transferência/genética
11.
PLoS One ; 15(3): e0226234, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32208422

RESUMO

The chloroplast genome harbors plenty of valuable information for phylogenetic research. Illumina short-read data is generally used for de novo assembly of whole plastomes. PacBio or Oxford Nanopore long reads are additionally employed in hybrid approaches to enable assembly across the highly similar inverted repeats of a chloroplast genome. Unlike for PacBio, plastome assemblies based solely on Nanopore reads are rarely found, due to their high error rate and non-random error profile. However, the actual quality decline connected to their use has rarely been quantified. Furthermore, no study has employed reference-based assembly using Nanopore reads, which is common with Illumina data. Using Leucanthemum Mill. as an example, we compared the sequence quality of seven chloroplast genome assemblies of the same species, using combinations of two sequencing platforms and three analysis pipelines. In addition, we assessed the factors which might influence Nanopore assembly quality during sequence generation and bioinformatic processing. The consensus sequence derived from de novo assembly of Nanopore data had a sequence identity of 99.59% compared to Illumina short-read de novo assembly. Most of the errors detected were indels (81.5%), and a large majority of them is part of homopolymer regions. The quality of reference-based assembly is heavily dependent upon the choice of a close-enough reference. When using a reference with 0.83% sequence divergence from the studied species, mapping of Nanopore reads results in a consensus comparable to that from Nanopore de novo assembly, and of only slightly inferior quality compared to a reference-based assembly with Illumina data. For optimal de novo assembly of Nanopore data, appropriate filtering of contaminants and chimeric sequences, as well as employing moderate read coverage, is essential. Based on these results, we conclude that Nanopore long reads are a suitable alternative to Illumina short reads in plastome phylogenomics. Few errors remain in the finalized assembly, which can be easily masked in phylogenetic analyses without loss in analytical accuracy. The easily applicable and cost-effective technology might warrant more attention by researchers dealing with plant chloroplast genomes.


Assuntos
Mapeamento Cromossômico , Genoma de Cloroplastos , Sequenciamento de Nucleotídeos em Larga Escala , Leucanthemum/genética , Nanoporos , Filogenia
12.
Mol Phylogenet Evol ; 147: 106784, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32135308

RESUMO

The Amelanchier-Malacomeles-Peraphyllum (AMP) clade consists of ca. 26 species distributed in North and Central America, Europe, Asia, and northwestern Africa. While molecular and morphological data strongly support this clade, relationships of its genera are uncertain. Support for the monophyly of Amelanchier and for the phylogenetic positions of Malacomeles and Peraphyllum has varied between studies. Our goals were to reconstruct a robust phylogeny of the AMP clade in the framework of Maleae and clarify the phylogenetic placements of Malacomeles and Peraphyllum. This study employs sequences of the whole plastome and nuclear ribosomal DNA (nrDNA) repeats assembled using genome skimming with 131 samples representing 115 species in 31 genera of Rosaceae, especially Maleae. Maximum likelihood (ML) and Bayesian analysis (BI) of whole plastome datasets strongly supported Amelanchier as not monophyletic, with Peraphyllum sister to eastern North American Amelanchier and Malacomeles sister to the western North American-Eurasian Amelanchier. In contrast, nrDNA recovered the monophyly of Amelanchier, with Peraphyllum sister to Amelanchier and Malacomeles sister to the Amelanchier-Peraphyllum clade. The strong topological conflicts between plastome and nrDNA phylogenies of Peraphyllum and of Malacomeles are best explained by ancient chloroplast capture that occurred in SW North America.


Assuntos
Núcleo Celular/genética , Cloroplastos/genética , DNA Ribossômico/genética , Genoma de Cloroplastos , Genômica/métodos , Filogenia , Rosaceae/classificação , Rosaceae/genética , Teorema de Bayes , Mapeamento Cromossômico , Evolução Molecular , Geografia , Rosaceae/anatomia & histologia , Análise de Sequência de DNA
13.
Mol Phylogenet Evol ; 147: 106802, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32217170

RESUMO

The walnut family Juglandaceae was widely distributed in the Northern Hemisphere while several extant genera now exhibit intercontinental disjunctions. Recent progress in the systematics of Juglandaceae has greatly broadened our knowledge about its origin and evolution. However, there are still uncertainties about the intergeneric relationships within Juglandaceae, and discrepancies between fossil records and inferred divergence times for certain lineages were observed. In this study, well-resolved phylogenies of the Juglandaceae are reconstructed based on both the nuclear RAD-Seq and the whole chloroplast genome data. Our results support the Juglandoideae topology of (Hicoreae, (Platycaryeae, Juglandeae)) at the tribal level. Within Juglandeae, a discordant position of Pterocarya was detected between nuclear and plastid genome data, and a more likely topology (nuclear), (Juglans, (Pterocarya, Cyclocarya)), was discussed based on evidence from molecular data and fossil records. Based on carefully selected fossil calibrations, the divergence times of extant lineages were estimated and they corroborated well with fossil records (especially concerning Juglans and Pterocarya). Four sections within Juglans were strongly supported by the nuclear data. Within Juglans, the incongruent position of J. hopeiensis was recovered between the nuclear and plastid genomes. Yet the origin and evolutionary history of J. cinerea and J. hopeiensis are supported to be complicated and need further clarification. Integrative evidence from the fossil records, phylogeny and lineage divergence times shows that Juglandoideae originated in North America, and migrated to Eurasia via both the Bering and the North Atlantic land bridges. Our study shows the potential of integrative biogeographic studies for illuminating the evolutionary history of Juglandaceae.


Assuntos
Núcleo Celular/genética , Genoma de Cloroplastos/genética , Juglandaceae/genética , Filogenia , Análise de Sequência de DNA , Evolução Molecular , Variação Genética , América do Norte , Fatores de Tempo
14.
Planta ; 251(3): 72, 2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32112137

RESUMO

MAIN CONCLUSION: This study provides broad insight into the chloroplast genomes of the subfamily Monsteroideae. The identified polymorphic regions may be suitable for designing unique and robust molecular markers for phylogenetic inference. Monsteroideae is the third largest subfamily (comprises 369 species) and one of the early diverging lineages of the monocot plant family Araceae. The phylogeny of this important subfamily is not well resolved at the species level due to scarcity of genomic resources and suitable molecular markers. Here, we report annotated chloroplast genome sequences of four Monsteroideae species: Spathiphyllum patulinervum, Stenospermation multiovulatum, Monstera adansonii, and Rhaphidophora amplissima. The quadripartite chloroplast genomes (size range 163,335-164,751 bp) consist of a pair of inverted repeats (25,270-25,931 bp), separating a small single copy region (21,448-22,346 bp) from a large single copy region (89,714-91,841 bp). The genomes contain 114 unique genes, including four rRNA genes, 80 protein-coding genes, and 30 tRNA genes. Gene features, amino acid frequencies, codon usage, GC contents, oligonucleotide repeats, and inverted repeats dynamics exhibit similarities among the four genomes. Higher rate of synonymous substitutions was observed as compared to non-synonymous substitutions in 76 protein-coding genes. Positive selection was observed in seven protein-coding genes, including psbK, ndhK, ndhD, rbcL, accD, rps8, and ycf2. Our included species of Araceae showed the monophyly in Monsteroideae and other subfamilies. We report 30 suitable polymorphic regions. The polymorphic regions identified here might be suitable for designing unique and robust markers for inferring the phylogeny and phylogeography among closely related species within the genus Spathiphyllum and among distantly related species within the subfamily Monsteroideae. The chloroplast genomes presented here are a valuable contribution towards understanding the molecular evolutionary dynamics in the family Araceae.


Assuntos
Araceae/classificação , Araceae/genética , Evolução Molecular , Genes de Plantas/genética , Genoma de Cloroplastos/genética , Filogenia , Composição de Bases , Sequência de Bases , Cloroplastos/genética , Uso do Códon , DNA de Plantas , Genes de RNAr , Componentes Genômicos , Tamanho do Genoma , Anotação de Sequência Molecular , Fases de Leitura Aberta , Folhas de Planta/genética , Proteínas de Plantas/genética , Polimorfismo Genético , RNA de Transferência/genética
15.
Gene ; 736: 144410, 2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32007581

RESUMO

Magnoliaceae is a primitive taxon in the angiosperms, comprising approximately 240 species in 2-17 genera. Many of them have been widely cultivated due to their horticultural and medicinal value. However, there are uncertainties and controversies about the delimitation of the genera except Liriodendron L. in this family. The Yulania taxa is also the focus of dispute at the genus and section levels. In this study, we compared ten Yulania plastomes, including the newly sequenced M. polytepala. The plastome-wide comparative analysis demonstrated that 1) Yulania cp genomes were highly conserved, and the majority differences existed in IR regions with the loss/retention of trnV-GAC or ycf15 gene, 2) mutational hotspots with high levels of nucleotide diversity (Pi > 0.02) existed in both coding (rpoA, and ycf1) and no-coding (ccsA-ndhD, ndhE-ndhG, ndhF-rpl32, petA-psbJ, rpl32-trnL, rps3-rps19, and trnH-psbA) regions among the genus Yulania. Combined with other data from Magnoliaceae plastomes, our reconstructed molecular phylogenetic tree revealed that Yulania is monophyletic, separated from the genus Magnolia L. (=Magnolia subg. Magnolia L.), but seems a sister of Michelia L. Moreover, M. polytepala which belongs to the genus Yulania is most closely related to M. liliiflora. All these results indicated that plastome data may contribute to investigating taxonomy, population genetics and phylogeny of Yulania.


Assuntos
Cloroplastos/genética , Genoma de Cloroplastos/genética , Genoma de Planta/genética , Magnolia/genética , Magnoliaceae/genética , Genética Populacional/métodos , Genômica/métodos , Magnoliopsida/genética , Filogenia
16.
BMC Genomics ; 21(1): 114, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32005143

RESUMO

BACKGROUND: Chloroplast (cp) genome information would facilitate the development and utilization of Taxodium resources. However, cp genome characteristics of Taxodium were poorly understood. RESULTS: We determined the complete cp genome sequences of T. distichum, T. mucronatum, and T. ascendens. The cp genomes are 131,947 bp to 132,613 bp in length, encode 120 genes with the same order, and lack typical inverted repeat (IR) regions. The longest small IR, a 282 bp trnQ-containing IR, were involved in the formation of isomers. Comparative analysis of the 3 cp genomes showed that 91.57% of the indels resulted in the periodic variation of tandem repeat (TR) motifs and 72.46% single nucleotide polymorphisms (SNPs) located closely to TRs, suggesting a relationship between TRs and mutational dynamics. Eleven hypervariable regions were identified as candidates for DNA barcode development. Hypothetical cp open reading frame 1(Ycf1) was the only one gene that has an indel in coding DNA sequence, and the indel is composed of a long TR. When extended to cupressophytes, ycf1 genes have undergone a universal insertion of TRs accompanied by extreme length expansion. Meanwhile, ycf1 also located in rearrangement endpoints of cupressophyte cp genomes. All these characteristics highlight the important role of repeats in the evolution of cp genomes. CONCLUSIONS: This study added new evidence for the role of repeats in the dynamics mechanism of cp genome mutation and rearrangement. Moreover, the information of TRs and hypervariable regions would provide reliable molecular resources for future research focusing on the infrageneric taxa identification, phylogenetic resolution, population structure and biodiversity for the genus Taxodium and Cupressophytes.


Assuntos
Cloroplastos/genética , Análise de Sequência de DNA/métodos , Taxodium/classificação , Evolução Molecular , Variação Genética , Tamanho do Genoma , Genoma de Cloroplastos , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Taxodium/genética
17.
J Genet ; 992020.
Artigo em Inglês | MEDLINE | ID: mdl-32089527

RESUMO

The base composition of the chloroplast genes is of great interest because they play a highly significant role in the evolutionary development of the plants. Evaluation of the 48 chloroplast protein-coding genes of Hemiptelea davidii showed that the average GC content was about 37.32%, while at the third codon base position alone the average GC content was only 27.80%. The 48 genes were classified into five groups based on the gene function and each group displayed specific codon characteristics. Based on the relative synonymous codon usage analysis, a total of 30 high-frequency codons and 11 optimal codons were identified, most of them ended with A or T. Neutrality plot, ENC-plot and PR2-plot analyses showed that the codon usage bias of the chloroplast genes of H. davidii was greatly influenced by natural selection pressures. Meanwhile, the frequency of codon usage of chloroplast genes among different plant species displayed similarities, with some synonymous codons were preferred to be used in H. davidii. In this study, the codon usage pattern of the chloroplast protein coding genes of H. davidii provides us with a better understanding of the expression of chloroplast genes, and may advice the future molecular breeding programmes.


Assuntos
Uso do Códon , Genes de Cloroplastos , Rosales/genética , Composição de Bases , Evolução Molecular , Genoma de Cloroplastos , Seleção Genética
18.
J Genet ; 992020.
Artigo em Inglês | MEDLINE | ID: mdl-32089532

RESUMO

Sophora alopecuroides belongs to the genus Sophora of the family Papilionoideae. It is mainly distributed in the desert and semidesert areas of northern China, and has high medicinal value and ecological function. Previous studies have reported the chemical composition and ecological functions of S. alopecuroides. However, only a few reports are available on the genomic information of S. alopecuroides, especially the chloroplast genome, which greatly limits the study of the evolutionary relationship between other species of Papilionoideae. Here, we report the complete chloroplast genome of S. alopecuroides. The size of the chloroplast genome is 155,207 bp, and the GC content is 36.44%. The S. alopecuroides chloroplast genome consists of 132 genes, including 83 protein-coding genes, 41 transfer RNA (tRNA) genes,and eight ribosomal RNA (rRNA) genes. Phylogenetic analysis revealed the taxonomic position of S. alopecuroides in Papilionoideae, and the genus Sophora and the genus Ammopiptanthus were highly related. Comparative genomics analysis revealed the gene rearrangement in the evolution of S. alopecuroides. The comparison between S. alopecuroides and the species of the Papilionoideae identified a novel 23 kb inversion between the trnC-GCA and trnF-GAA which occurred before the divergence of Sophora and Ammopiptanthus of Thermopsideae. This study provided an essential data for the understanding of phylogenetic status of S. alopecuroides.


Assuntos
Genoma de Cloroplastos , Genômica , Filogenia , Sophora/classificação , Sophora/genética , Biologia Computacional/métodos , Sequência Conservada , Genes de Cloroplastos , Genômica/métodos , Sequenciamento de Nucleotídeos em Larga Escala , Repetições de Microssatélites , Anotação de Sequência Molecular , Fenótipo , Sequências Repetitivas de Ácido Nucleico
19.
Gene ; 731: 144340, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-31923575

RESUMO

As a member of the large Brassicaceae family, yellow mustard (Sinapis alba L.) has been used as an important gene pool for the genetic improvement of cash crops in Brassicaceae. Understanding the phylogenetic relationship between Sinapis alba (S. alba) and other Brassicaceae crops can provide guidance on the introgression of its favorable alleles into related species. The chloroplast (cp) genome is an ideal model for assessing genome evolution and the phylogenetic relationships of complex angiosperm families. Herein, we de novo assembled the complete cp genome of S. alba by integrating the PacBio and Illumina sequencing platforms. A 153,760 bp quadripartite cycle without any gap was obtained, including a pair of inverted repeats (IRa and IRb) of 26,221 bp, separated by a large single copy (LSC) region of 83,506 bp and a small single copy (SSC) region of 17,821 bp. A total of 78 protein-coding genes, 30 tRNA genes, and four rRNA genes were identified in this cp genome, as were 89 simple sequence repeat (SSR) loci of 18 types. The codon usage analysis revealed a preferential use of the Leu codon with the A/U ending. The phylogenetic analysis using 82 Brassicaceae species demonstrated that S. alba had a close relationship with important Brassica and Raphanus species; moreover, it likely originated from a separate evolutionary pathway compared with the congeneric Sinapis arvensis. The synonymous (Ks) and non-synonymous (Ks) substitution rate analysis showed that genes encoding "Subunits of cytochrome b/f complex" were under the lowest purifying selection pressure, whereas those associated with "Maturase", "Subunit of acetyl-CoA", and "Subunits of NADH-dehydrogenase" underwent relatively higher purifying selection pressures. Our results provide valuable information for fully utilizing the S. alba cp genome as a potential genetic resource for the genetic improvement of Brassica and Raphanus species.


Assuntos
Brassicaceae/classificação , Brassicaceae/genética , Genoma de Cloroplastos/genética , Mostardeira/genética , Sinapis/genética , Cloroplastos/genética , Evolução Molecular , Sequenciamento de Nucleotídeos em Larga Escala , Mostardeira/classificação , Mostardeira/citologia , Filogenia , Raphanus/classificação , Raphanus/citologia , Raphanus/genética , Análise de Sequência de DNA/métodos , Sinapis/classificação , Sinapis/citologia , Sequenciamento Completo do Genoma
20.
Gene ; 732: 144355, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31935501

RESUMO

Curcuma is an important member of Zingiberaceae. Many species of this genus are widely used in traditional medicine and have important cultural value in East Asia. Among them, C. longa is considered to be the main source of curcumin and has a very wide range of uses. The rapid development of molecular phylogeny has deepened our understanding of taxonomy and evolution of Curcuma. However, little is known about the chloroplast genome phylogeny and the genetic bases of adaptative evolution. In this work, we sequenced the complete chloroplast genome of 4 Curcuma species. Curcuma chloroplast genomes showed highly conserved structures and the length ranged from 159,423 bp to 152,723 bp. A total of 133 genes were observed. Multiple repeats and simple sequence repeats (SSRs) were detected. By comparing with related species, 7 highly variable regions were identified as potential specific DNA barcodes for species identification. Phylogenetic analysis of complete plastome sequences and specific data sets revealed discordance with expected genus boundary. Chloroplast phylogenetic relationships were better predicted by geography than by morphological and nuclear DNA, indicating a substantial existence of introgression. 9 genes were proved to have high posteriori probability in positive selection analysis, and 4 of them (psbA, psbD, PetA and rbcL) closely related to photosynthesis, implying that chloroplast genes may had undergone positive selection pressure in evolution. These results are of great significance for us to understand the genetic basis, phylogeny and adaptive evolution of Curcuma chloroplast.


Assuntos
Curcuma/classificação , Genoma de Cloroplastos , Sequenciamento Completo do Genoma/métodos , Cloroplastos/genética , Curcuma/citologia , Curcuma/genética , Evolução Molecular , Tamanho do Genoma , Repetições de Microssatélites , Filogenia
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