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Chloroplast Genomes and Comparative Analyses among Thirteen Taxa within Myrsinaceae s.str. Clade (Myrsinoideae, Primulaceae).

ABSTRACT: The Myrsinaceae s.str. clade is a tropical woody representative in Myrsinoideae of Primulaceae and has ca. 1300 species. The generic limits and alignments of this clade are unclear due to the limited number of genetic markers and/or taxon samplings in previous studies. Here, the chloroplast (cp) genomes of 13 taxa within the Myrsinaceae s.str. clade are sequenced and characterized. These cp genomes are typical quadripartite circle molecules and are highly conserved in size and gene content. Three pseudogenes are identified, of which ycf15 is totally absent from five taxa. Noncoding and large single copy region (LSC) exhibit higher levels of nucleotide diversity (Pi) than other regions. A total of ten hotspot fragments and 796 chloroplast simple sequence repeats (SSR) loci are found across all cp genomes. The results of phylogenetic analysis support the notion that the monophyletic Myrsinaceae s.str. clade has two subclades. Non-synonymous substitution rates (dN) are higher in housekeeping (HK) genes than photosynthetic (PS) genes, but both groups have a nearly identical synonymous substitution rate (dS). The results indicate that the PS genes are under stronger functional constraints compared with the HK genes. Overall, the study provides hypervariable molecular markers for phylogenetic reconstruction and contributes to a better understanding of plastid gene evolution in Myrsinaceae s.str. clade.

SUBMITTER: Yan X

PROVIDER: S-EPMC6769889 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Chloroplast Genomes and Comparative Analyses among Thirteen Taxa within Myrsinaceae s.str. Clade (Myrsinoideae, Primulaceae).

Yan Xiaokai X Liu Tongjian T Yuan Xun X Xu Yuan Y Yan Haifei H Hao Gang G

International journal of molecular sciences 20190913 18

The Myrsinaceae s.str. clade is a tropical woody representative in Myrsinoideae of Primulaceae and has ca. 1300 species. The generic limits and alignments of this clade are unclear due to the limited number of genetic markers and/or taxon samplings in previous studies. Here, the chloroplast (cp) genomes of 13 taxa within the Myrsinaceae s.str. clade are sequenced and characterized. These cp genomes are typical quadripartite circle molecules and are highly conserved in size and gene content. Thre ...[more]

PMID: 31540236

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Project description:The genus Primula (Primulaceae) comprises more than 500 species, with 300 species distributed in China. The contradictory results between systematic analyses and morphology-based taxonomy make taxonomy studies difficult. Furthermore, frequent introgression between closely related species of Primula can result in non-monophyletic species. In this study, the complete chloroplast genome of sixteen Primula obconica subsp. obconica individuals were assembled and compared with 84 accessions of 74 species from 21 sections of the 24 sections of the genus in China. The plastome sizes of P. obconica subsp. obconica range from 153,584 bp to 154,028 bp. Genome-wide variations were detected, and 1915 high-quality SNPs and 346 InDels were found. Most SNPs were detected in downstream and upstream gene regions (45.549% and 41.91%). Two cultivated accessions, ZP1 and ZP2, were abundant with SSRs. Moreover, 12 SSRs shared by 9 accessions showed variations that may be used as molecular markers for population genetic studies. The phylogenetic tree showed that P. obconica subsp. obconica cluster into two independent clades. Two subspecies have highly recognizable morphological characteristics, isolated geographical distribution areas, and distinct phylogenetic relationships compared with P. obconica subsp. obconica. We elevate the two subspecies of P. obconica to separate species. Our phylogenetic tree is largely inconsistent with morphology-based taxonomy. Twenty-one sections of Primula were mainly divided into three clades. The monophyly of Sect. Auganthus, Sect. Minutissimae, Sect. Sikkimensis, Sect. Petiolares, and Sect. Ranunculoides are well supported in the phylogenetic tree. The Sect. Obconicolisteri, Sect. Monocarpicae, Sect. Carolinella, Sect. Cortusoides, Sect. Aleuritia, Sect. Denticulata, Sect. Proliferae Pax, and Sect. Crystallophlomis are not a monophyletic group. The possible explanations for non-monophyly may be hybridization, polyploidization, recent introgression, incorrect taxonomy, or chloroplast capture. Multiple genomic data and population genetic studies are therefore needed to reveal the evolutionary history of Primula. Our results provided valuable information for intraspecific variation and phylogenetic relationships within Primula.

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Dataset Information

Chloroplast Genomes and Comparative Analyses among Thirteen Taxa within Myrsinaceae s.str. Clade (Myrsinoideae, Primulaceae).

Publications

Chloroplast Genomes and Comparative Analyses among Thirteen Taxa within Myrsinaceae s.str. Clade (Myrsinoideae, Primulaceae).

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