Project description:Yeasts are leading model organisms for mitochondrial genome studies. The explosion of complete sequence of yeast mitochondrial (mt) genomes revealed a wide diversity of organization and structure between species. Recently, genome-wide polymorphism survey on the mt genome of isolates of a single species, Lachancea kluyveri, was also performed. To compare the mitochondrial genome evolution at two hierarchical levels: within and among closely related species, we focused on five species of the Lachancea genus, which are close relatives of L. kluyveri. Hence, we sequenced the complete mt genome of L. dasiensis, L. nothofagi, L. mirantina, L. fantastica and L. meyersii. The phylogeny of the Lachancea genus was explored using these data. Analysis of intra- and interspecific variability across the whole Lachancea genus led to the same conclusions regarding the mitochondrial genome evolution. These genomes exhibit a similar architecture and are completely syntenic. Nevertheless, genome sizes vary considerably because of the variations of the intergenic regions and the intron content, contributing to mitochondrial genome plasticity. The high variability of the intergenic regions stands in contrast to the high level of similarity of protein sequences. Quantification of the selective constraints clearly revealed that most of the mitochondrial genes are under purifying selection in the whole genus.
Project description:Tilia is a complex genus in the family Malvaceae that has high ecological and economical values. Owing to the lack of sufficient distinguishable morphological and molecular characteristics, interspecific relationships in this genus are not clear. Chloroplast (cp) genomes are small, meanwhile most angiosperms usually undergo matrilineal inheritance. Consequently, they can be used in molecular systematics and phylogenetic analyses. Here, we sequenced and assembled cp genomes from T. endochrysea, T. tomentosa, T. miqueliana, T. americana and T. cordata, and compared them with those of seven previously reported Tilia species. Similar gene contents, gene orders and GC contents existed among the 12 cp genomes, which ranged from 162,564 to 162,855 bp and encoded 113 unique genes. Abundant simple sequence repeats (119-127) and dispersed repeats (97-135) were detected in Tilia cp genomes. In total, 11 hypervariable regions were identified that could be suitable for species identification and phylogenetic studies. A phylogenetic analysis of Malvaceae based on 5 hypervariable genes (matK + ndhF + rpoB + rpoC2+ycf1) revealed that all eight subfamilies were monophyletic groups. Additionally, the genus Tilia was divided into three groups on the basis of all 521 molecular variation loci. The current study provides valuable insights into the genomic evolution of the genus Tilia.
Project description:Saccharum complex includes genera Saccharum, Miscanthus, Erianthus, Narenga, and Tripidium. Since the Saccharum complex/Saccharinae constitutes the gene pool used by sugarcane breeders to introduce useful traits into sugarcane, studying the genomic characterization of the Saccharum complex has become particularly important. Here, we assembled graph-based mitochondrial genomes (mitogenomes) of four Saccharinae species (T. arundinaceum, E. rockii, M. sinensis, and N. porphyrocoma) using Illumina and PacBio sequencing data. The total lengths of the mitogenomes of T. arundinaceum, M. sinensis, E. rockii and N. porphyrocoma were 549,593 bp, 514,248 bp, 481,576 bp and 513,095 bp, respectively. Then, we performed a comparative mitogenomes analysis of Saccharinae species, including characterization, organelles transfer sequence, collinear sequence, phylogenetics analysis, and gene duplicated/loss. Our results provided the mitogenomes of four species closely related to sugarcane breeding, enriching the mitochondrial genomic resources of the Saccharinae. Additionally, our study offered new insights into the evolution of mitogenomes at the family and genus levels and enhanced our understanding of organelle evolution in the highly polyploid Saccharum genus.
Project description:BackgroundNeocinnamomum plants are considered a promising feedstock for biodiesel in China, due to the richness in long-chain fatty acids (LCFAs) found in their seeds. However, the mitochondrial genome (mitogenome) of this genus has not yet been systematically described, and the exploration of species relationships within this genus using mitogenome sequences is also an uncharted territory. This has hindered our understanding of mitogenome diversity and the evolutionary relationships within Neocinnamomum.ResultsIn this study, a total of 24 individuals representing seven distinct taxa from the genus Neocinnamomum were subjected to Illumina sequencing, and the species N. delavayi was sequenced using Oxford Nanopore sequencing technology. We successfully assembled the mitogenome of N. delavayi, which is 778,066 bp in size and exhibits a single circular structure. The analysis identified 659 dispersed repeats, 211 simple sequence repeats (SSRs), and 30 tandem repeats within the mitogenome. Additionally, 37 homologous fragments, totaling 9929 bp, were found between the mitogenome and the plastid genome (plastome). The codons of 41 protein-coding genes (PCGs) had a preference for ending in A/T, and the codon usage bias of the majority of these genes was influenced by natural selection pressures. Comparative genomic analysis revealed low collinearity and significant gene rearrangements between species. Phylogenetic analysis resulted in the classification of Neocinnamomum into six distinct clades, contradicting previous findings which based on complete plastomes and nuclear ribosomal cistron (nrDNA). In the PCGs of 24 individuals, 86 mutation events were identified, which included three indels and 83 SNPs. Notably, the ccmC gene underwent positive selection in pairwise comparisons of three species pairs. Furthermore, 748 RNA editing sites were predicted within the PCGs of the N. delavayi mitogenome.ConclusionsThis study enriches our knowledge of the mitogenomes in the family Lauraceae, and provides valuable data and a foundation for genomic evolution research, genetic resource conservation, and molecular breeding in Neocinnamomum.
Project description:The genus Aphanomyces (Saprolegniales, Oomycetes) includes species with a variety of ecologies from saprotrophs to plant and animal parasites. Two important species in this genus are A. astaci, the cause of crayfish plague and its close relative, A. invadans, which causes the epizootic ulcerative syndrome on fish. In this study, we have assembled and annotated the mitochondrial (mt) genomes of A. astaci and A. invadans from the whole genome shotgun sequence reads (PRJNA187372; PRJNA258292, respectively). The assembly was generated from A. astaci Pc-genotype strain APO3 and A. invadans strain NJM9701. The sizes of the mtDNAs were 49,489 bp and 49,061 bp for A. astaci and A. invadans, respectively. The species shared similar genetic content and organization encoding 35 proteins, two ribosomal RNAs, three putative open reading frames and 33 transfer RNAs of 19 amino acids for peptide synthesis. Both species also had a large inverted repeat region (LIR) of approximately 12 kb, the LIR contained large and small ribosomal RNAs and eight protein coding genes. These annotated mt genomes serve as a valuable genetic backbone for further development of diagnostic methods and phylogenetic and migration studies of the animal parasitic species of Aphanomyces.
Project description:Most species of Papilionidae are large and beautiful ornamental butterflies. They are recognized as model organisms in ecology, evolutionary biology, genetics, and conservation biology but present numerous unresolved phylogenetic problems. Complete mitochondrial genomes (mitogenomes) have been widely used in phylogenetic studies of butterflies, but mitogenome knowledge within the family Papilionidae is limited, and its phylogeny is far from resolved. In this study, we first report the mitogenome of Byasa confusa from the subfamily Papilioninae of Papilionidae. The mitogenome of B. confusa is 15,135 bp in length and contains 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and an AT-rich control region (CR), closely mirroring the genomic structure observed in related butterfly species. Comparative analysis of 77 Papilionidae mitogenomes shows gene composition and order to be identical to that of an ancestral insect, and the AT bias, Ka/Ks, and relative synonymous codon usage (RSCU) are all consistent with that of other reported butterfly mitogenomes. We conducted phylogenetic analyses using maximum-likelihood (ML) and Bayesian-inference (BI) methods, with 77 Papilionidae species as ingroups and two species of Nymphalidae and Lycaenidae as outgroups. The phylogenetic analysis indicated that B. confusa were clustered within Byasa. The phylogenetic trees show the monophyly of the subfamily Papilioninae and the tribes Leptocircini, Papilionini, and Troidini. The data supported the following relationships in tribe level on Papilioninae: (((Troidini + Papilionini) + Teinopalpini) + Leptocircini). The divergence time analysis suggests that Papilionidae originated in the late Creataceous. Overall, utilizing the largest number of Papilionidae mitogenomes sequenced to date, with the current first exploration in a phylogenetic analysis on Papilionidae (including four subfamilies), this study comprehensively reveals the mitogenome characteristics and mitogenome-based phylogeny, providing information for further studies on the mitogenome, phylogeny, evolution, and taxonomic revision of the Papilionidae family.
Project description:BackgroundThis study was motivated by the observation of unusual mitochondrial haplotype distributions and associated physiological differences between populations of the killifish Fundulus heteroclitus distributed along the Atlantic coast of North America. A distinct "northern" haplotype is fixed in all populations north of New Jersey, and does not appear south of New Jersey except in extreme upper-estuary fresh water habitats, and northern individuals are known to be more tolerant of hyposmotic conditions than southern individuals. Complete mitochondrial genomes were sequenced from individuals from northern coastal, southern coastal, and fresh water populations (and from out-groups). Comparative genomics approaches were used to test multiple evolutionary hypotheses proposed to explain among-population genome variation including directional selection and hybridization.ResultsStructure and organization of the Fundulus mitochondrial genome is typical of animals, yet subtle differences in substitution patterns exist among populations. No signals of directional selection or hybridization were detected. Mitochondrial genes evolve at variable rates, but all genes exhibit very low dN/dS ratios across all lineages, and the southern population harbors more synonymous polymorphism than other populations.ConclusionEvolution of mitochondrial genomes within Fundulus is primarily governed by interaction between strong purifying selection and demographic influences, including larger historical population size in the south. Though directional selection and hybridization hypotheses were not supported, adaptive processes may indirectly contribute to partitioning of variation between populations.
Project description:Bacteria of the genus Elizabethkingia are emerging infectious agents that can cause infection in humans. The number of published whole-genome sequences of Elizabethkingia is rapidly increasing. In this study, we used comparative genomics to investigate the genomes of the six species in the Elizabethkingia genus, namely E. meningoseptica, E. anophelis, E. miricola, E. bruuniana, E. ursingii, and E. occulta. In silico DNA-DNA hybridization, whole-genome sequence-based phylogeny, pan genome analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed, and clusters of orthologous groups were evaluated. Of the 86 whole-genome sequences available in GenBank, 21 were complete genome sequences and 65 were shotgun sequences. In silico DNA-DNA hybridization clearly delineated the six Elizabethkingia species. Phylogenetic analysis confirmed that E. bruuniana, E. ursingii, and E. occulta were closer to E. miricola than to E. meningoseptica and E. anophelis. A total of 2,609 clusters of orthologous groups were identified among the six type strains of the Elizabethkingia genus. Metabolism-related clusters of orthologous groups accounted for the majority of gene families in KEGG analysis. New genes were identified that substantially increased the total repertoire of the pan genome after the addition of 86 Elizabethkingia genomes, which suggests that Elizabethkingia has shown adaptive evolution to environmental change. This study presents a comparative genomic analysis of Elizabethkingia, and the results of this study provide knowledge that facilitates a better understanding of this microorganism.
Project description:Glycyrrhiza (Fabaceae) species are rich in metabolites and widely used in medicine. Research on the chloroplast genome of Glycyrrhiza is important for understanding its phylogenetics, biogeography, genetic diversity, species identification, and medicinal properties. In this study, comparative genomics and phylogenomics of Glycyrrhiza were analyzed based on the chloroplast genome. The chloroplast genomes of six Glycyrrhiza species were obtained using various assembly and annotation tools. The final assembled chloroplast genome sizes for the six Glycyrrhiza species ranged from 126,380 bp to 129,115 bp, with a total of 109-110 genes annotated. Comparative genomics results showed that the chloroplast genomes of Glycyrrhiza showed typically lacking inverted repeat regions, and the genome length, structure, GC content, codon usage, and gene distribution were highly similar. Bioinformatics analysis revealed the presence of 69-96 simple sequence repeats and 61-138 long repeats in the chloroplast genomes. Combining the results of mVISTA and nucleotide diversity, four highly variable regions were screened for species identification and relationship studies. Selection pressure analysis indicated overall purifying selection in the chloroplast genomes of Glycyrrhiza, with a few positively selected genes potentially linked to environmental adaptation. Phylogenetic analyses involving all tribes of Fabaceae with published chloroplast genomes elucidated the evolutionary relationships, and divergence time estimation estimated the chronological order of species differentiations within the Fabaceae family. The results of phylogenetic analysis indicated that species from the six subfamilies formed distinct clusters, consistent with the classification scheme of the six subfamilies. In addition, the inverted repeat-lacking clade in the subfamily Papilionoideae clustered together, and it was the last to differentiate. Co-linear analysis confirmed the conserved nature of Glycyrrhiza chloroplast genomes, and instances of gene rearrangements and inversions were observed in the subfamily Papilionoideae.