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Comparative chloroplast genome analyses of Avena: insights into evolutionary dynamics and phylogeny.

ABSTRACT: BACKGROUND:Oat (Avena sativa L.) is a recognized health-food, and the contributions of its different candidate A-genome progenitor species remain inconclusive. Here, we report chloroplast genome sequences of eleven Avena species, to examine the plastome evolutionary dynamics and analyze phylogenetic relationships between oat and its congeneric wild related species. RESULTS:The chloroplast genomes of eleven Avena species (size range of 135,889-135,998?bp) share quadripartite structure, comprising of a large single copy (LSC; 80,014-80,132?bp), a small single copy (SSC; 12,575-12,679?bp) and a pair of inverted repeats (IRs; 21,603-21,614?bp). The plastomes contain 131 genes including 84 protein-coding genes, eight ribosomal RNAs and 39 transfer RNAs. The nucleotide sequence diversities (Pi values) range from 0.0036 (rps19) to 0.0093 (rpl32) for ten most polymorphic genes and from 0.0084 (psbH-petB) to 0.0240 (petG-trnW-CCA) for ten most polymorphic intergenic regions. Gene selective pressure analysis shows that all protein-coding genes have been under purifying selection. The adjacent position relationships between tandem repeats, insertions/deletions and single nucleotide polymorphisms support the evolutionary importance of tandem repeats in causing plastome mutations in Avena. Phylogenomic analyses, based on the complete plastome sequences and the LSC intermolecular recombination sequences, support the monophyly of Avena with two clades in the genus. CONCLUSIONS:Diversification of Avena plastomes is explained by the presence of highly diverse genes and intergenic regions, LSC intermolecular recombination, and the co-occurrence of tandem repeat and indels or single nucleotide polymorphisms. The study demonstrates that the A-genome diploid-polyploid lineage maintains two subclades derived from different maternal ancestors, with A. longiglumis as the first diverging species in clade I. These genome resources will be helpful in elucidating the chloroplast genome structure, understanding the evolutionary dynamics at genus Avena and family Poaceae levels, and are potentially useful to exploit plastome variation in making hybrids for plant breeding.

SUBMITTER: Liu Q

PROVIDER: S-EPMC7466839 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Comparative chloroplast genome analyses of Avena: insights into evolutionary dynamics and phylogeny.

Liu Qing Q Li Xiaoyu X Li Mingzhi M Xu Wenkui W Schwarzacher Trude T Heslop-Harrison John Seymour JS

BMC plant biology 20200902 1

<h4>Background</h4>Oat (Avena sativa L.) is a recognized health-food, and the contributions of its different candidate A-genome progenitor species remain inconclusive. Here, we report chloroplast genome sequences of eleven Avena species, to examine the plastome evolutionary dynamics and analyze phylogenetic relationships between oat and its congeneric wild related species.<h4>Results</h4>The chloroplast genomes of eleven Avena species (size range of 135,889-135,998 bp) share quadripartite struct ...[more]

PMID: 32878602

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Project description:The Polygonatum genus represents a perennial herb with the Liliaceae family, boasting substantial economic and medicinal significance. The majority of Polygonatum plants exhibit notable similarity while lacking distinctive identifying characteristics, thus resulting in the proliferation of adulterated medicinal materials within the market. Within this study, we conducted an in-depth analysis of the complete chloroplast (cp) genomes of four Polygonatum plants and compared them with four closely akin species. The primary objectives were to unveil structural variations, species divergence, and the phylogenetic interrelations among taxa. The cp genomes of the four Polygonatum species were typified by a conventional quadripartite structure, incorporating a large single copy region (LSC), a small single copy region (SSC), and a pair of inverted repeat regions. In total, we annotated a range of 131 to 133 genes, encompassing 84 to 86 protein-coding genes, 38 transfer RNA (tRNA) genes, 8 ribosomal RNA (rRNA) genes, and 0 to 2 pseudogenes (ycf1, infA). Our comparative analyses unequivocally revealed a remarkable consistency in gene order and GC content within the Polygonatum genus. Furthermore, we predicted a potential 59 to 64 RNA editing sites distributed across 22 protein-coding genes, with the ndhB gene exhibiting the most prominent propensity for RNA editing sites, boasting a tally of 15 sites. Notably, six regions of substantial potential variability were ascertained, characterized by elevated Pi values. Noteworthy, molecular markers for species identification, population genetic scrutiny, and phylogenetic investigations within the genus were identified in the form of the psaJ-rpl33 and trnS + trnT-psaD barcodes. The resultant phylogenetic tree unequivocally depicted the formation of a monophyletic clade comprising species within the evolutionary framework of Liliaceae, demonstrating closer evolutionary affinities with Maianthemum, Dracaeneae, and Asparageae. This comprehensive compendium of findings collectively contributes to the advancement of molecular species identification, elucidation of phylogenetic interrelationships, and the establishment of DNA barcodes tailored to the Polygonatum species.

Project description:BackgroundChloroplast genome resources can provide useful information for the evolution of plant species. Tea plant (Camellia sinensis) is among the most economically valuable member of Camellia. Here, we determined the chloroplast genome of the first natural triploid Chinary type tea ('Wuyi narcissus' cultivar of Camellia sinensis var. sinensis, CWN) and conducted the genome comparison with the diploid Chinary type tea (Camellia sinensis var. sinensis, CSS) and two types of diploid Assamica type teas (Camellia sinensis var. assamica: Chinese Assamica type tea, CSA and Indian Assamica type tea, CIA). Further, the evolutionary mechanism of the chloroplast genome of Camellia sinensis and the relationships of Camellia species based on chloroplast genome were discussed.ResultsComparative analysis showed the evolutionary dynamics of chloroplast genome of Camellia sinensis were the repeats and insertion-deletions (indels), and distribution of the repeats, indels and substitutions were significantly correlated. Chinese tea and Indian tea had significant differences in the structural characteristic and the codon usage of the chloroplast genome. Analysis of sequence characterized amplified region (SCAR) using sequences of the intergenic spacers (trnE/trnT) showed none of 292 different Camellia sinensis cultivars had similar sequence characteristic to triploid CWN, but the other four Camellia species did. Estimations of the divergence time showed that CIA diverged from the common ancestor of two Assamica type teas about 6.2 Mya (CI: 4.4-8.1 Mya). CSS and CSA diverged to each other about 0.8 Mya (CI: 0.4-1.5 Mya). Moreover, phylogenetic clustering was not exactly consistent with the current taxonomy of Camellia.ConclusionsThe repeat-induced and indel-induced mutations were two important dynamics contributed to the diversification of the chloroplast genome in Camellia sinensis, which were not mutually exclusive. Chinese tea and Indian tea might have undergone different selection pressures. Chloroplast transfer occurred during the polyploid evolution in Camellia sinensis. In addition, our results supported the three different domestication origins of Chinary type tea, Chinese Assamica type tea and Indian Assamica type tea. And, the current classification of some Camellia species might need to be further discussed.

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Comparative chloroplast genome analyses of Avena: insights into evolutionary dynamics and phylogeny.

Publications

Comparative chloroplast genome analyses of Avena: insights into evolutionary dynamics and phylogeny.

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