Dataset Information

Evolutionary analysis of six chloroplast genomes from three Persea americana ecological races: Insights into sequence divergences and phylogenetic relationships.

ABSTRACT: Chloroplasts significantly influence species phylogenies because of their maternal inheritance and the moderate evolutionary rate of their genomes. Avocado, which is a member of the family Lauraceae, has received considerable attention from botanists, likely because of its position as a basal angiosperm. However, there is relatively little avocado genomic information currently available. In this study, six complete avocado chloroplast genomes from three ecological races were assembled to examine the sequence diversity among the three avocado ecological races. A comparative genomic analysis revealed that 515 simple sequence repeat loci and 176 repeats belonging to four other types were polymorphic across the six chloroplast genomes. Three highly variable regions (trnC-GCA-petN, petN-psbM, and petA-psbJ) were identified as highly informative markers. A phylogenetic analysis based on 79 common protein-coding genes indicated that the six examined avocado accessions from three ecological races form a monophyletic clade. The other three genera belonging to the Persea group clustered to form a sister clade with a high bootstrap value. These chloroplast genomes provide important genetic information for future attempts at identifying avocado races and for the related biological research.

SUBMITTER: Ge Y

PROVIDER: S-EPMC6750585 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Evolutionary analysis of six chloroplast genomes from three Persea americana ecological races: Insights into sequence divergences and phylogenetic relationships.

Ge Yu Y Dong Xiangshu X Wu Bin B Wang Nan N Chen Di D Chen Haihong H Zou Minghong M Xu Zining Z Tan Lin L Zhan Rulin R

PloS one 20190918 9

Chloroplasts significantly influence species phylogenies because of their maternal inheritance and the moderate evolutionary rate of their genomes. Avocado, which is a member of the family Lauraceae, has received considerable attention from botanists, likely because of its position as a basal angiosperm. However, there is relatively little avocado genomic information currently available. In this study, six complete avocado chloroplast genomes from three ecological races were assembled to examine ...[more]

PMID: 31532782

Similar Datasets

Project description:The debate on the origin and evolution of flowers has recently entered the field of developmental genetics, with focus on the design of the ancestral floral regulatory program. Flowers can differ dramatically among angiosperm lineages, but in general, sterile perianth organs surrounding stamens (male reproductive organs) and carpels (female reproductive organs) constitute the basic floral structure. However, the basal angiosperm lineages exhibit spectacular diversity in the number, arrangement, and structure, of floral organs, while the evolutionarily derived monocot and eudicot lineages share a far more uniform floral ground plan. As such, regulatory mechanisms underlying the archetypal floral plan, for instance that of the eudicot genetic model Arabidopsis thaliana, are unlikely to apply to the original flowers. Here we show that broadly overlapping transcriptional programs characterise the floral transcriptome of the basal angiosperm Persea americana (avocado), while floral gene expression domains are typically organ-specific in Arabidopsis. Our findings extend the âfading bordersâ model for basal angiosperms from organ identity genes to the downstream floral transcriptome, and suggest that the combinatorial mechanism for organ identity may not operate in basal angiosperms as it does in Arabidopsis. Furthermore, fading expression of components of the stamen transcriptome in central and peripheral regions of Persea flowers resembles the developmental program of the hypothesized gymnosperm âfloral progenitorâ. Accordingly, in contrast to the canalized organ-specific regulatory apparatus of Arabidopsis, floral development may have been originally regulated by overlapping transcriptional cascades with fading gradients of influence from focal to bordering organs. Expression profiles of inflorescence buds, pre-meiotic floral buds, inner and outer tepals, stamens, carpels, initiating fruit, and leaves were assessed in an interwoven double loop design for eight samples with 16 arrays. Sample materials were collected from two individuals (biological replicates) cultivated on the University of Floridaâs Gainesville campus, and RNA was isolated twice for technical replication. Thus, four RNA extractions from each of the eight tissue types listed above were individually labeled with Cy3 (twice) or Cy5 (twice) and hybridized with four other Cy3 or Cy5 labeled samples as a dual channel array system.

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.

Project description:The Brassica genus comprises many economically important worldwide cultivated crops. The well-established model of the Brassica genus, U's triangle, consists of three basic diploid plant species (Brassica rapa, Brassica oleracea, and Brassica nigra) and three amphidiploid species (Brassica napus, Brassica juncea, and Brassica carinata) that arose through interspecific hybridizations. Despite being extensively studied because of its commercial relevance, several aspects of the origin of the Brassica species and the relationships within and among these six species still remain open questions. Here, we successfully de novo assembled 60 complete chloroplast genomes of Brassica genotypes of all six species. A complete map of the single nucleotide variants and insertions and deletions in the chloroplast genomes of different Brassica species was produced. The chloroplast genome consists of a Large and a Small Single Copy (LSC and SSC) region between two inverted repeats, and while these regions of chloroplast genomes have very different molecular evolutionary rates, phylogenetic analyses of different regions yielded no contradicting topologies and separated the Brassica genus into four clades. B. carinata and B. juncea share their chloroplast genome with one of their hybridization donors B. nigra and B. rapa, respectively, which fits the U model. B. rapa, surprisingly, shows evidence of two types of chloroplast genomes, with one type specific to some Italian broccoletto accessions. B. napus clearly has evidence for two independent hybridization events, as it contains either B. rapa chloroplast genomes. The divergence estimation suggests that B. nigra and B. carinata diverged from the main Brassica clade 13.7 million years ago (Mya), while B. rapa and B. oleracea diverged at 2.18 Mya. The use of the complete chloroplast DNA sequence not only provides insights into comparative genome analysis but also paves the way for a better understanding of the phylogenetic relationships within the Brassica genus.

Project description:The genus Alchemilla L., known for its medicinal and ornamental value, is widely distributed in the Holarctic regions with a few species found in Asia and Africa. Delimitation of species within Alchemilla is difficult due to hybridization, autonomous apomixes, and polyploidy, necessitating efficient molecular-based characterization. Herein, we report the initial complete chloroplast (cp) genomes of Alchemilla. The cp genomes of two African (Afromilla) species Alchemilla pedata and Alchemilla argyrophylla were sequenced, and phylogenetic and comparative analyses were conducted in the family Rosaceae. The cp genomes mapped a typical circular quadripartite structure of lengths 152,438 and 152,427 base pairs (bp) in A. pedata and A. argyrophylla, respectively. Alchemilla cp genomes were composed of a pair of inverted repeat regions (IRa/IRb) of length 25,923 and 25,915 bp, separating the small single copy (SSC) region of 17,980 and 17,981 bp and a large single copy (LSC) region of 82,612 and 82,616 bp in A. pedata and A. argyrophylla, respectively. The cp genomes encoded 114 unique genes including 88 protein-coding genes, 37 transfer RNA (tRNA) genes, and 4 ribosomal RNA (rRNA) genes. Additionally, 88 and 95 simple sequence repeats (SSRs) and 37 and 40 tandem repeats were identified in A. pedata and A. argyrophylla, respectively. Significantly, the loss of group II intron in atpF gene in Alchemilla species was detected. Phylogenetic analysis based on 26 whole cp genome sequences and 78 protein-coding gene sequences of 27 Rosaceae species revealed a monophyletic clustering of Alchemilla nested within subfamily Rosoideae. Based on a protein-coding region, negative selective pressure (Ka/Ks < 1) was detected with an average Ka/Ks value of 0.1322 in A. argyrophylla and 0.1418 in A. pedata. The availability of complete cp genome in the genus Alchemilla will contribute to species delineation and further phylogenetic and evolutionary studies in the family Rosaceae.

Dataset Information

Evolutionary analysis of six chloroplast genomes from three Persea americana ecological races: Insights into sequence divergences and phylogenetic relationships.

Publications

Evolutionary analysis of six chloroplast genomes from three Persea americana ecological races: Insights into sequence divergences and phylogenetic relationships.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets