Dataset Information

Plastome Characterization and Phylogenomic Analysis Yield New Insights into the Evolutionary Relationships among the Species of the Subgenus Bryocles (Hosta; Asparagaceae) in East Asia.

ABSTRACT: The genus Hosta, which has a native distribution in temperate East Asia and a number of species ranging from 23 to 40, represents a taxonomically important and ornamentally popular plant. Despite its taxonomic and horticultural importance, the genus Hosta has remained taxonomically challenging owing to insufficient diagnostic features, continuous morphological variation, and the process of hybridization and introgression, making species circumscription and phylogenetic inference difficult. In this study, we sequenced 11 accessions of Hosta plastomes, including members of three geographically defined subgenera, Hosta, Bryocles, and Giboshi, determined the characteristics of plastomes, and inferred their phylogenetic relationships. We found highly conserved plastomes among the three subgenera, identified several mutation hotspots that can be used as barcodes, and revealed the patterns of codon usage bias and RNA editing sites. Five positively selected plastome genes (rbcL, rpoB, rpoC2, rpl16, and rpl20) were identified. Phylogenetic analysis suggested (1) the earliest divergence of subg. Hosta, (2) non-monophyly of subg. Bryocles and its two sections (Lamellatae and Stoloniferae), (3) a sister relationship between H. sieboldiana (subg. Giboshi) and H. ventricosa (subg. Bryocles), and (4) reciprocally monophyletic and divergent lineages of H. capitata in Korea and Japan, requiring further studies of their taxonomic distinction.

SUBMITTER: Yang J

PROVIDER: S-EPMC8538707 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature

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Plastome Characterization and Phylogenomic Analysis Yield New Insights into the Evolutionary Relationships among the Species of the Subgenus Bryocles (Hosta; Asparagaceae) in East Asia.

Yang JiYoung J Choi Mi-Jung MJ Kim Seon-Hee SH Choi Hyeok-Jae HJ Kim Seung-Chul SC

Plants (Basel, Switzerland) 20210922 10

The genus Hosta, which has a native distribution in temperate East Asia and a number of species ranging from 23 to 40, represents a taxonomically important and ornamentally popular plant. Despite its taxonomic and horticultural importance, the genus Hosta has remained taxonomically challenging owing to insufficient diagnostic features, continuous morphological variation, and the process of hybridization and introgression, making species circumscription and phylogenetic inference di ...[more]

PMID: 34685791

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Project description:Hosta species are abundant in northeastern Asia, offering significant ornamental and horticultural value due to their diverse foliage colors and textures, as well as their showy, fragrant flowers. Among the eight taxa naturally distributed in Korea, H. clausa is found in central and northern Korea, as well as northeastern China, providing valuable resources for developing and improving new varieties. Currently, four intraspecific taxa of H. clausa are recognized at the variety level based on reproductive (opened vs. closed perianth), vegetative (leaf shape), and habitat characteristics: var. clausa, var. normalis, var. ensata, and var. geumgangensis. Despite its horticultural and taxonomic importance, little is known about the degree of intraspecific chloroplast genome variation and relationships among the varieties of H. clausa. This could provide some valuable information for marker-assisted breeding programs and molecular cultivar identification. In this study, we investigated the complete plastid genome of 14 accessions of H. clausa, covering its native distribution range. We characterized genome size and features and performed comparative plastome analyses (frequency of codon usage, nucleotide diversity, mutation hotspots). Our analysis revealed highly conserved structures and gene content organization in H. clausa, along with significantly (two to three times) lower nucleotide diversity compared to intraspecific herbaceous and woody species. The phylogenetic analysis did not support the recognition of intraspecific taxa as currently delimited, and a broad-scale geographical structure of complete plastomes was not apparent. The asexual reproductive mode of H. clausa appears to contribute to the low plastome genetic diversity. A total of 72 polymorphic sites identified among 14 accessions of H. clausa and their phylogenetic relationships, in conjunction with their geographical distribution and morphological characteristics, will be a valuable resource for barcoding study, marker-assisted breeding programs, and developing conservation strategies for hosta species in East Asia.

Project description:We analyzed variations in chloroplast DNA (cpDNA) in the widespread herbaceous species Hosta sieboldiana and Hosta albomarginata across large portions of their geographic ranges in the Japanese archipelago. Our objective was to compare the phylogeographic histories and phylogeographic structures of the two congeneric species in the Japanese archipelago. The location of the study is Japanese archipelago. We sequenced 1380 bp of noncoding cpDNA from 45 populations of H. sieboldiana (n = 362) and 55 populations of H. albomarginata (n = 436) to assess genetic variations within and among populations across almost the entire distributions of the species in Japan. Extant patterns of geographic structure were analyzed using statistical parsimony networks and spatial analysis of molecular variance (SAMOVA). We also used Monmonier's algorithm to detect genetic barriers between regions. Relationships between the populations were examined using a neighbor-joining (NJ) method. Four haplotypes were found for H. sieboldiana, whereas eight haplotypes were identified for H. albomarginata. Total genetic haplotype diversity (hT) and within-population haplotype diversity (hS) for H. sieboldiana were 0.352 and 0.040, respectively, while the values for H. albomarginata were 0.529 and 0.085, respectively. The population differentiations (GST) for H. sieboldiana and H. albomarginata were 0.839 and 0.886, respectively. The SAMOVA analysis revealed two clusters in H. sieboldiana and four clusters in H. albomarginata. Differentiations between and among the clusters were supported by the BARRIER analysis and the NJ tree. We detected differences in the population genetic structure between the two species. We found that H. sieboldiana had lower haplotype diversity than H. albomarginata. These results may be partially explained by the difference in ecological habitats and geographic distributions between the species. Hosta albomarginata is more widely distributed than H. sieboldiana in East Asia including Russia, and this large distribution range would enable more chances to intraspecific gene flow.

Project description:BackgroudPaeonia holds considerable value in medicinal, ornamental horticultural, and edible oil industries, but the incomplete state of phylogenetic research in this genus poses a challenge to the effective conservation and development of wild germplasm, and also impedes the practical utilization of existing cultivars. Due to its uniparental inheritance and lack of recombination, the plastome (i.e., plastid genome), which is a valuable molecular marker for phylogenetic analyses, is characterized by an appropriate rate of nucleotide evolution.MethodsIn this study, 10 newly assembled data and available reported data were combined to perform a comparative genomics and phylogenetics analysis of 63 plastomes of 16 Paeonia species, primarily from East Asia, which is the origin and diversity center of Paeonia.ResultsRanging between 152,153 and 154,405 bp, most plastomes displayed a conserved structure and relatively low nucleotide diversity, except for six plastomes, which showed obvious IR construction or expansion. A total of 111 genes were annotated in the Paeonia plastomes. Four genes (rpl22, rps3, rps19 and ycf1) showed different copy numbers among accessions while five genes (rpl36, petN, psbI, rpl33 and psbJ) showed strong codon usage biases (ENC < 35). Additional selection analysis revealed that no genes were under positive selection during the domestication of tree peony cultivars whereas four core photosynthesis-related genes (petA, psaA, psaB and rbcL) were under positive selection in herbaceous peony cultivars. This discovery might contribute to the wide adaption of these cultivars. Two types of molecular markers (SSR and SNP) were generated from the 63 plastomes. Even though SSR was more diverse than SNP, it had a weaker ability to delimit Paeonia species than SNP. The reconstruction of a phylogenetic backbone of Paeonia in East Asia revealed significant genetic divergence within the P. ostii groups. Evidence also indicated that the majority of P. suffruticosa cultivars had a maternal origin, from P. ostii. The results of this research also suggest that P. delavayi var. lutea, which likely resulted from hybridization with P. ludlowii, should be classified as a lineage within the broader P. delavayi group.ConclusionsOverall, this study's research findings suggest that the Paeonia plastome is highly informative for phylogenetic and comparative genomic analyses, and could be useful in future research related to taxonomy, evolution, and domestication.

Project description:BackgroundArtemisia in East Asia includes a number of economically important taxa that are widely used for food, medicinal, and ornamental purposes. The identification of taxa, however, has been hampered by insufficient diagnostic morphological characteristics and frequent natural hybridization. Development of novel DNA markers or barcodes with sufficient resolution to resolve taxonomic issues of Artemisia in East Asia is significant challenge.ResultsTo establish a molecular basis for taxonomic identification and comparative phylogenomic analysis of Artemisia, we newly determined 19 chloroplast genome (plastome) sequences of 18 Artemisia taxa in East Asia, de novo-assembled and annotated the plastomes of two taxa using publicly available Illumina reads, and compared them with 11 Artemisia plastomes reported previously. The plastomes of Artemisia were 150,858-151,318 base pairs (bp) in length and harbored 87 protein-coding genes, 37 transfer RNAs, and 8 ribosomal RNA genes in conserved order and orientation. Evolutionary analyses of whole plastomes and 80 non-redundant protein-coding genes revealed that the noncoding trnH-psbA spacer was highly variable in size and nucleotide sequence both between and within taxa, whereas the coding sequences of accD and ycf1 were under weak positive selection and relaxed selective constraints, respectively. Phylogenetic analysis of the whole plastomes based on maximum likelihood and Bayesian inference analyses yielded five groups of Artemisia plastomes clustered in the monophyletic subgenus Dracunculus and paraphyletic subgenus Artemisia, suggesting that the whole plastomes can be used as molecular markers to infer the chloroplast haplotypes of Artemisia taxa. Additionally, analysis of accD and ycf1 hotspots enabled the development of novel markers potentially applicable across the family Asteraceae with high discriminatory power.ConclusionsThe complete sequences of the Artemisia plastomes are sufficiently polymorphic to be used as super-barcodes for this genus. It will facilitate the development of new molecular markers and study of the phylogenomic relationships of Artemisia species in the family Asteraceae.

Project description:Lobelia species, as rich source of the alkaloid lobeline which has been shown to have important biological activity, have been used in folk medicine throughout East Asia to treat various diseases. However, Lobelia is a complex and varied genus in East Asia and is thus difficult to identify. Genomic resources would aid identification, however the availability of such information is poor, preventing a clear understanding of their evolutionary history from being established. To close this gap in the available genomic data, in this study, 17 plastomes of East Asian lobelias were newly sequenced and assembled. Although the plastomes of Lobelia sect. Hypsela, L. sect. Speirema, and L. sect. Rhynchopetalum shared the gene structure, the inverted repeat (IR)/large single copy (LSC) boundaries, genome size, and the number of repeats were variable, indicating the non-conservative nature of plastome evolution within these sections. However, the genomes of the Lobelia sect. Delostemon and L. sect. Stenotium showed rearrangements, revealing that these two sections might have undergone different evolutionary histories. We assessed nine hotspot genes and 27-51 simple sequence repeat motifs, which will also serve as valuable DNA barcode regions in future population genetics studies and for the delineation of plant species. Our phylogenetic analysis resolved the evolutionary positions of the five sections in agreement with previous evolutionary trees based on morphological features. Although phylogenetic reconstruction of Lobelioideae based on the rpoC2 gene has rarely been performed, our results indicated that it contains a considerable amount of phylogenetic information and offers great promise for further phylogenetic analysis of Lobelioideae. Our site-specific model identified 173 sites under highly positive selections. The branch-site model exhibited 11 positive selection sites involving four genes in the East Asian branches. These four genes may play critical roles in the adaptation of East Asian taxa to diverse environments. Our study is the first to detect plastome organization, phylogenetic utility, and signatures of positive selection in the plastomes of East Asian lobelias, which will help to further advance taxonomic and evolutionary studies and the utilization of medicinal plant resources.

Dataset Information

Plastome Characterization and Phylogenomic Analysis Yield New Insights into the Evolutionary Relationships among the Species of the Subgenus Bryocles (Hosta; Asparagaceae) in East Asia.

Publications

Plastome Characterization and Phylogenomic Analysis Yield New Insights into the Evolutionary Relationships among the Species of the Subgenus <i>Bryocles</i> (<i>Hosta</i>; Asparagaceae) in East Asia.

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