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The Complete Chloroplast Genomes of Echinacanthus Species (Acanthaceae): Phylogenetic Relationships, Adaptive Evolution, and Screening of Molecular Markers.

ABSTRACT: Among the four species of Echinacanthus (Acanthaceae), one distributed in the West Himalayan region and three restricted to the Sino-Vietnamese karst region. Because of its ecological significance, molecular markers are necessary for proper assessment of its genetic diversity and phylogenetic relationships. Herein, the complete chloroplast genomes of four Echinacanthus species were determined for the first time. The results indicated that all the chloroplast genomes were mapped as a circular structure and each genomes included 113 unique genes, of which 80 were protein-coding, 29 were tRNAs, and 4 were rRNAs. However, the four cp genomes ranged from 151,333 to 152,672 bp in length. Comparison of the four cp genomes showed that the divergence level was greater between geographic groups. We also analyzed IR expansion or contraction in the four cp genomes and the fifth type of the large single copy/inverted repeat region in Lamiales was suggested. Furthermore, based on the analyses of comparison and nucleotide variability, six most divergent sequences (rrn16, ycf1, ndhA, rps16-trnQ-UUG, trnS-GCU-trnG-UCC, and psaA-ycf3) were identified. A total of 37-45 simple sequence repeats were discovered in the four species and 22 SSRs were identified as candidate effective molecular markers for detecting interspecies polymorphisms. These SSRs and hotspot regions could be used as potential molecular markers for future study. Phylogenetic analysis based on Bayesian and parsimony methods did not support the monophyly of Echinacanthus. The phylogenetic relationships among the four species were clearly resolved and the results supported the recognition of the Sino-Vietnamese Echinacanthus species as a new genus. Based on the protein sequence evolution analysis, 12 genes (rpl14, rpl16, rps4, rps15, rps18, rps19, psbK, psbN, ndhC, ndhJ, rpoB, and infA) were detected under positive selection in branch of Sino-Vietnamese Echinacanthus species. These genes will lead to understanding the adaptation of Echinacanthus species to karst environment. The study will help to resolve the phylogenetic relationship and understand the adaptive evolution of Echinacanthus. It will also provide genomic resources and potential markers suitable for future species identification and speciation studies of the genus.

SUBMITTER: Gao C

PROVIDER: S-EPMC6335349 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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The Complete Chloroplast Genomes of Echinacanthus Species (Acanthaceae): Phylogenetic Relationships, Adaptive Evolution, and Screening of Molecular Markers.

Gao Chunming C Deng Yunfei Y Wang Jun J

Frontiers in plant science 20190110

Among the four species of Echinacanthus (Acanthaceae), one distributed in the West Himalayan region and three restricted to the Sino-Vietnamese karst region. Because of its ecological significance, molecular markers are necessary for proper assessment of its genetic diversity and phylogenetic relationships. Herein, the complete chloroplast genomes of four Echinacanthus species were determined for the first time. The results indicated that all the chloroplast genomes were mapped as ...[more]

PMID: 30687376

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Project description:BackgroundCommelinaceae (Commelinales) comprise 41 genera and are widely distributed in both the Old and New Worlds, except in Europe. The relationships among genera in this family have been suggested in several morphological and molecular studies. However, it is difficult to explain their relationships due to high morphological variations and low support values. Currently, many researchers have been using complete chloroplast genome data for inferring the evolution of land plants. In this study, we completed 15 new plastid genome sequences of subfamily Commelinoideae using the Mi-seq platform. We utilized genome data to reveal the structural variations and reconstruct the problematic positions of genera for the first time.ResultsAll examined species of Commelinoideae have three pseudogenes (accD, rpoA, and ycf15), and the former two might be a synapomorphy within Commelinales. Only four species in tribe Commelineae presented IR expansion, which affected duplication of the rpl22 gene. We identified inversions that range from approximately 3 to 15 kb in four taxa (Amischotolype, Belosynapsis, Murdannia, and Streptolirion). The phylogenetic analysis using 77 chloroplast protein-coding genes with maximum parsimony, maximum likelihood, and Bayesian inference suggests that Palisota is most closely related to tribe Commelineae, supported by high support values. This result differs significantly from the current classification of Commelinaceae. Also, we resolved the unclear position of Streptoliriinae and the monophyly of Dichorisandrinae. Among the ten CDS (ndhH, rpoC2, ndhA, rps3, ndhG, ndhD, ccsA, ndhF, matK, and ycf1), which have high nucleotide diversity values (Pi > 0.045) and over 500 bp length, four CDS (ndhH, rpoC2, matK, and ycf1) show that they are congruent with the topology derived from 77 chloroplast protein-coding genes.ConclusionsIn this study, we provide detailed information on the 15 complete plastid genomes of Commelinoideae taxa. We identified characteristic pseudogenes and nucleotide diversity, which can be used to infer the family evolutionary history. Also, further research is needed to revise the position of Palisota in the current classification of Commelinaceae.

Project description:BackgroundSorbus sensu stricto (Sorbus s.s.) is a genus with important economical values because of its beautiful leaves, and flowers and especially the colorful fruits. It belongs to the tribe Maleae of the family Rosaceae, and comprises about 90 species mainly distributed in China. There is on-going dispute about its infrageneric classification and species delimitation as the species are morphologically similar. With the aim of shedding light on the circumscription of taxa within the genus, phylogenetic analyses were performed using 29 Sorbus s.s. chloroplast (cp) genomes (16 newly sequenced) representing two subgenera and eight sections.ResultsThe 16 cp genomes newly sequenced range between 159,646 bp and 160,178 bp in length. All the samples examined and 22 taxa re-annotated in Sorbus sensu lato (Sorbus s.l.) contain 113 unique genes with 19 of these duplicated in the inverted repeat (IR). Six hypervariable regions including trnR-atpA, petN-psbM, rpl32-trnL, trnH-psbA, trnT-trnL and ndhC-trnV were screened and 44-53 SSRs and 14-31 dispersed repeats were identified as potential molecular markers. Phylogenetic analyses under ML/BI indicated that Sorbus s.l. is polyphyletic, but Sorbus s.s. and the other five segregate genera, Aria, Chamaemespilus, Cormus, Micromeles and Torminalis are monophyletic. Two major clades and four sub-clades resolved with full-support within Sorbus s.s. are not consistent with the existing infrageneric classification. Two subgenera, subg. Sorbus and subg. Albocarmesinae are supported as monophyletic when S. tianschanica is transferred to subg. Albocarmesinae from subg. Sorbus and S. hupehensis var. paucijuga transferred to subg. Sorbus from subg. Albocarmesinae, respectively. The current classification at sectional level is not supported by analysis of cp genome phylogeny.ConclusionPhylogenomic analyses of the cp genomes are useful for inferring phylogenetic relationships in Sorbus s.s. Though genome structure is highly conserved in the genus, hypervariable regions and repeat sequences used are the most promising molecule makers for population genetics, species delimitation and phylogenetic studies.

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Dataset Information

The Complete Chloroplast Genomes of Echinacanthus Species (Acanthaceae): Phylogenetic Relationships, Adaptive Evolution, and Screening of Molecular Markers.

Publications

The Complete Chloroplast Genomes of <i>Echinacanthus</i> Species (Acanthaceae): Phylogenetic Relationships, Adaptive Evolution, and Screening of Molecular Markers.

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