Dataset Information

Chloroplast Genomes for Five Skeletonema Species: Comparative and Phylogenetic Analysis.

ABSTRACT: Skeletonema species are cosmopolitan coastal diatoms that exhibit important roles in ecological system. The chloroplast genomes (cpDNAs) have been proven to be important in the study of molecular evolution and genetic diversity. However, cpDNA of only a single Skeletonema species (S. pseudocostatum) has been constructed, hindering in-depth investigation on Skeletonema species. In this study, complete cpDNAs of five Skeletonema species were constructed with cpDNAs of four species S. marinoi, S. tropicum, S. costatum, and S. grevillea constructed for the first time. These cpDNAs had similar sizes and same numbers of genes. These cpDNAs were highly syntenic with no substantial expansions, contractions, or inversions. Interestingly, two copies of petF, which encodes ferredoxin with critical role in iron dependency, were found in all five Skeletonema species, with one copy in the cpDNA and another copy in the nuclear genome of each species. Selection analysis revealed that all PCGs of cpDNAs were undergoing purifying selection. Despite the high conservation of these cpDNAs, nine genomic regions with high sequence divergence were identified, which illustrated substantial variations that could be used as markers for phylogenetic inference and for tracking Skeletonema species in the field. Additionally, the numbers of simple sequence repeats varied among different cpDNAs, which were useful for detecting genetic polymorphisms. The divergence times estimated using PCGs of cpDNAs revealed that most of these species were established within ∼33 Mya, consistent with that estimated using mtDNAs. Overall, the current study deepened our understanding about the molecular evolution of Skeletonema cpDNAs.

SUBMITTER: Liu S

PROVIDER: S-EPMC8710728 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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Chloroplast Genomes for Five Skeletonema Species: Comparative and Phylogenetic Analysis.

Liu Shuya S Xu Qing Q Liu Kuiyan K Zhao Yongfang Y Chen Nansheng N

Frontiers in plant science 20211213

Skeletonema species are cosmopolitan coastal diatoms that exhibit important roles in ecological system. The chloroplast genomes (cpDNAs) have been proven to be important in the study of molecular evolution and genetic diversity. However, cpDNA of only a single Skeletonema species (S. pseudocostatum) has been constructed, hindering in-depth investigation on Skeletonema species. In this study, complete cpDNAs of five Skeletonema species were constructed with cpDN ...[more]

PMID: 34966403

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Project description:Polygonatum Miller belongs to the tribe Polygonateae of Asparagaceae. The horizontal creeping fleshy roots of several species in this genus serve as traditional Chinese medicine. Previous studies have mainly reported the size and gene contents of the plastomes, with little information on the comparative analysis of the plastid genomes of this genus. Additionally, there are still some species whose chloroplast genome information has not been reported. In this study, the complete plastomes of six Polygonatum were sequenced and assembled, among them, the chloroplast genome of P. campanulatum was reported for the first time. Comparative and phylogenetic analyses were then conducted with the published plastomes of three related species. Results indicated that the whole plastome length of the Polygonatum species ranged from 154,564 bp (P. multiflorum) to 156,028 bp (P. stenophyllum) having a quadripartite structure of LSC and SSC separated by two IR regions. A total of 113 unique genes were detected in each of the species. Comparative analysis revealed that gene content and total GC content in these species were highly identical. No significant contraction or expansion was observed in the IR boundaries among all the species except P. sibiricum1, in which the rps19 gene was pseudogenized owing to incomplete duplication. Abundant long dispersed repeats and SSRs were detected in each genome. There were five remarkably variable regions and 14 positively selected genes were identified among Polygonatum and Heteropolygonatum. Phylogenetic results based on chloroplast genome strongly supported the placement of P. campanulatum with alternate leaves in sect. Verticillata, a group characterized by whorled leaves. Moreover, P. verticillatum and P. cyrtonema were displayed as paraphyletic. This study revealed that the characters of plastomes in Polygonatum and Heteropolygonatum maintained a high degree of similarity. Five highly variable regions were found to be potential specific DNA barcodes in Polygonatum. Phylogenetic results suggested that leaf arrangement was not suitable as a basis for delimitation of subgeneric groups in Polygonatum and the definitions of P. cyrtonema and P. verticillatum require further study.

Dataset Information

Chloroplast Genomes for Five Skeletonema Species: Comparative and Phylogenetic Analysis.

Publications

Chloroplast Genomes for Five <i>Skeletonema</i> Species: Comparative and Phylogenetic Analysis.

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