Tartary buckwheat （Fagopyrum tataricum） is an important pseudocereal crop that is strongly adapted to growth in adverse environments. Its gluten-free grain contains complete proteins with a well-balanced composition...Tartary buckwheat （Fagopyrum tataricum） is an important pseudocereal crop that is strongly adapted to growth in adverse environments. Its gluten-free grain contains complete proteins with a well-balanced composition of essential amino acids and is a rich source of beneficial phytochemicals that provide significant health benefits. Here, we report a high-quality, chromosome-scale Tartary buckwheat genome sequence of- 489.3 Mb that is assembled by combining whole-genome shotgun sequencing of both Illumina short reads and single-molecule real-time long reads, sequence tags of a large DNA insert fosmid library, Hi-C sequencing data, and BioNano genome maps. We annotated 33 366 high-confidence protein-coding genes based on expression evidence. Comparisons of the intra-genome with the sugar beet genome revealed an independent whole-genome duplication that occurred in the buckwheat lineage after they diverged from the common ancestor, which was not shared with rosids or asterids. The reference genome facilitated the identification of many new genes predicted to be involved in rutin biosynthesis and regulation, aluminum stress resistance, and in drought and cold stress responses. Our data suggest that Tartary buckwheat＇s ability to tolerate high levels of abiotic stress is attributed to the expansion of several gene families involved in signal transduction, gene regulation, and membrane transport. The availability of these genomic resources will facilitate the discovery of agronomically and nutritionally important genes and genetic improvement of Tartary buckwheat.展开更多
Gene duplications provide evolutionary potentials for generating novel functions, while polyploidization or whole genome duplication （WGD） doubles the chromosomes initially and results in hundreds to thousands of re...Gene duplications provide evolutionary potentials for generating novel functions, while polyploidization or whole genome duplication （WGD） doubles the chromosomes initially and results in hundreds to thousands of retained duplicates. WGDs are strongly supported by evidence commonly found in many species-rich lineages of eukaryotes, and thus are considered as a major driving force in species diversification. We per- formed comparative genomic and phylogenomic analyses of 59 public genomes/transcriptomes and 46 newly sequenced transcriptomes covering major lineages of angiosperms to detect large-scale gene dupli- cation events by surveying tens of thousands of gene family trees. These analyses confirmed most of the previously reported WGDs and provided strong evidence for novel ones in many lineages. The detected WGDs supported a model of exponential gene loss during evolution with an estimated half-life of approx- imately 21.6 million years, and were correlated with both the emergence of lineages with high degrees of diversification and periods of global climate changes. The new datasets and analyses detected many novel WGDs widely spread during angiosperm evolution, uncovered preferential retention of gene functions in essential cellular metabolisms, and provided clues for the roles of WGD in promoting angiosperm radiation and enhancing their adaptation to environmental changes.展开更多
Gene loss following whole genome duplication （WGD） is often biased, with one subgenome retaining more ancestral genes and the other sustaining more gene deletions. While bias toward the greater expression of gene co...Gene loss following whole genome duplication （WGD） is often biased, with one subgenome retaining more ancestral genes and the other sustaining more gene deletions. While bias toward the greater expression of gene copies on one subgenome can explain bias in gene loss, this raises the question to what drives differences in gene expression levels between subgenomes. Differences in chromatin modifications and epigenetic markers between subgenomes in several model species are now being identified, providing an explanation for bias in gene expression between subgenomes. WGDs can be classified into duplications with higher, biased gene loss and bias in gene expression between subgenomes versus those with lower, unbiased rates of gene loss and an absence of detectable bias between subgenomes; however, the origi- nally proposed link between these two classes and whether WGD results from an allo- or autopolyploid event is inconsistent with recent data from the allopolyploid Capsella bursa-pastoris. The gene balance hypothesis can explain bias in the functional categories of genes retained following WGD, the difference in gene loss rates between unbiased and biased WGDs, and how plant genomes have avoided being overrun with genes encoding dose-sensitive subunits of multiprotein complexes. Comparisons of gene expression patterns between retained transcription factor pairs in maize suggest the high degree of retention for WGD-derived pairs of transcription factors may instead be explained by the older duplication-degeneration-complementation model.展开更多
全基因组复制在动植物中普遍存在,被认为是促进物种进化的重要动力之一。作为蕨类植物的单种科物种,翼盖蕨(Didymochlaena trancatula)是真水龙骨类I的基部类群,在蕨类中具有独特的演化地位。本研究基于高通量测序,通过同义替换率(Ks)...全基因组复制在动植物中普遍存在,被认为是促进物种进化的重要动力之一。作为蕨类植物的单种科物种,翼盖蕨(Didymochlaena trancatula)是真水龙骨类I的基部类群,在蕨类中具有独特的演化地位。本研究基于高通量测序,通过同义替换率(Ks)分析、相对定年分析揭示翼盖蕨的全基因组复制发生情况。Ks分析表明,翼盖蕨至少经历了两次全基因组复制事件,其中一次发生于59–62 million years ago (Mya),另一次发生于90–94 Mya,这两次全基因组复制事件分别和白垩纪第三纪的Cretaceous-Tertiary(C-T)大灭绝事件以及翼盖蕨的物种分化时间相吻合。进一步对两次全基因组复制保留的基因进行功能注释和富集分析,结果显示与转录及代谢调控相关的基因优势被保留。翼盖蕨的全基因组复制事件可能促进了该物种的分化及其对极端环境的适应性。展开更多
Hox genes, responsible for regional specification along the anteroposterior axis in embryogenesis, are found as clusters in most eumetazoan genomes sequenced to date. Invertebrates possess a single Hox gene cluster wi...Hox genes, responsible for regional specification along the anteroposterior axis in embryogenesis, are found as clusters in most eumetazoan genomes sequenced to date. Invertebrates possess a single Hox gene cluster with some exceptions of secondary cluster breakages, while osteichthyans （bony vertebrates） have multiple Hox clusters. In tetrapods, four Hox clusters, derived from the so-called two-round whole genome duplications （2R-WGDs）, are observed. Overall, the number of Hox gene clusters has been regarded as a reliable marker of ploidy levels in animal genomes. In fact, this scheme also fits the situations in teleost fishes that experienced an additional WGD. In this review, I focus on cyclostomes and cartilaginous fishes as lineages that would fill the gap between invertebrates and osteichthyans. A recent study highlighted a possible loss of the HoxC cluster in the galeomorph shark lineage, while other aspects of cartilaginous fish Hox clusters usually mark their conserved nature. In contrast, existing resources suggest that the cyclostomes exhibit a different mode of Hox cluster organization. For this group of species, whose genomes could have differently responded to the 2R-WGDs from jawed vertebrates, therefore the number of Hox clusters may not serve as a good indicator of their ploidy level.展开更多
Whole genome duplication （WGD） events have been proven to occur in the evolutionary history of most angiosperms. Tomato is considered a model species of the Solanaceae family. In this study, we describe the details ...Whole genome duplication （WGD） events have been proven to occur in the evolutionary history of most angiosperms. Tomato is considered a model species of the Solanaceae family. In this study, we describe the details of the evolutionary process of the tomato genome by detecting collinearity blocks and dating the WGD events on the tree of life by combining two different methods： synonymous substitution rates （Ks） and phylogenetic trees. In total, 593 collinearity blocks were discovered out of 12 pseudo-chromosomes con- structed. It was evident that chromosome 2 had experienced an intra-chromosomat duplication event. Major inter-chromosomal dupli- cation occurred among all the pseudo-chromosome. We calculated the Ks value of these collinearity blocks. Two peaks of Ks distribution were found, corresponding to two WGD events occurring approximately 36-82 million years ago （MYA） and 148--205 MYA. Additionally, the results of phylogenetic trees suggested that the more recent WGD event may have occurred after the divergence of the rosidasterid clade, but before the major diversification in Solanaceae. The older WGD event was shown to have occurred before the divergence of the rosid-asterid clade and after the divergence of rice-Arabidopsis （monocot-dicot）.展开更多
文摘Tartary buckwheat （Fagopyrum tataricum） is an important pseudocereal crop that is strongly adapted to growth in adverse environments. Its gluten-free grain contains complete proteins with a well-balanced composition of essential amino acids and is a rich source of beneficial phytochemicals that provide significant health benefits. Here, we report a high-quality, chromosome-scale Tartary buckwheat genome sequence of- 489.3 Mb that is assembled by combining whole-genome shotgun sequencing of both Illumina short reads and single-molecule real-time long reads, sequence tags of a large DNA insert fosmid library, Hi-C sequencing data, and BioNano genome maps. We annotated 33 366 high-confidence protein-coding genes based on expression evidence. Comparisons of the intra-genome with the sugar beet genome revealed an independent whole-genome duplication that occurred in the buckwheat lineage after they diverged from the common ancestor, which was not shared with rosids or asterids. The reference genome facilitated the identification of many new genes predicted to be involved in rutin biosynthesis and regulation, aluminum stress resistance, and in drought and cold stress responses. Our data suggest that Tartary buckwheat＇s ability to tolerate high levels of abiotic stress is attributed to the expansion of several gene families involved in signal transduction, gene regulation, and membrane transport. The availability of these genomic resources will facilitate the discovery of agronomically and nutritionally important genes and genetic improvement of Tartary buckwheat.
文摘Gene duplications provide evolutionary potentials for generating novel functions, while polyploidization or whole genome duplication （WGD） doubles the chromosomes initially and results in hundreds to thousands of retained duplicates. WGDs are strongly supported by evidence commonly found in many species-rich lineages of eukaryotes, and thus are considered as a major driving force in species diversification. We per- formed comparative genomic and phylogenomic analyses of 59 public genomes/transcriptomes and 46 newly sequenced transcriptomes covering major lineages of angiosperms to detect large-scale gene dupli- cation events by surveying tens of thousands of gene family trees. These analyses confirmed most of the previously reported WGDs and provided strong evidence for novel ones in many lineages. The detected WGDs supported a model of exponential gene loss during evolution with an estimated half-life of approx- imately 21.6 million years, and were correlated with both the emergence of lineages with high degrees of diversification and periods of global climate changes. The new datasets and analyses detected many novel WGDs widely spread during angiosperm evolution, uncovered preferential retention of gene functions in essential cellular metabolisms, and provided clues for the roles of WGD in promoting angiosperm radiation and enhancing their adaptation to environmental changes.
文摘Gene loss following whole genome duplication （WGD） is often biased, with one subgenome retaining more ancestral genes and the other sustaining more gene deletions. While bias toward the greater expression of gene copies on one subgenome can explain bias in gene loss, this raises the question to what drives differences in gene expression levels between subgenomes. Differences in chromatin modifications and epigenetic markers between subgenomes in several model species are now being identified, providing an explanation for bias in gene expression between subgenomes. WGDs can be classified into duplications with higher, biased gene loss and bias in gene expression between subgenomes versus those with lower, unbiased rates of gene loss and an absence of detectable bias between subgenomes; however, the origi- nally proposed link between these two classes and whether WGD results from an allo- or autopolyploid event is inconsistent with recent data from the allopolyploid Capsella bursa-pastoris. The gene balance hypothesis can explain bias in the functional categories of genes retained following WGD, the difference in gene loss rates between unbiased and biased WGDs, and how plant genomes have avoided being overrun with genes encoding dose-sensitive subunits of multiprotein complexes. Comparisons of gene expression patterns between retained transcription factor pairs in maize suggest the high degree of retention for WGD-derived pairs of transcription factors may instead be explained by the older duplication-degeneration-complementation model.
文摘全基因组复制在动植物中普遍存在,被认为是促进物种进化的重要动力之一。作为蕨类植物的单种科物种,翼盖蕨(Didymochlaena trancatula)是真水龙骨类I的基部类群,在蕨类中具有独特的演化地位。本研究基于高通量测序,通过同义替换率(Ks)分析、相对定年分析揭示翼盖蕨的全基因组复制发生情况。Ks分析表明,翼盖蕨至少经历了两次全基因组复制事件,其中一次发生于59–62 million years ago (Mya),另一次发生于90–94 Mya,这两次全基因组复制事件分别和白垩纪第三纪的Cretaceous-Tertiary(C-T)大灭绝事件以及翼盖蕨的物种分化时间相吻合。进一步对两次全基因组复制保留的基因进行功能注释和富集分析,结果显示与转录及代谢调控相关的基因优势被保留。翼盖蕨的全基因组复制事件可能促进了该物种的分化及其对极端环境的适应性。
基金supported by the Young Scholar Fund from University of Konstanz and grants from German Research Foundation(KU2669/1-1)
文摘Hox genes, responsible for regional specification along the anteroposterior axis in embryogenesis, are found as clusters in most eumetazoan genomes sequenced to date. Invertebrates possess a single Hox gene cluster with some exceptions of secondary cluster breakages, while osteichthyans （bony vertebrates） have multiple Hox clusters. In tetrapods, four Hox clusters, derived from the so-called two-round whole genome duplications （2R-WGDs）, are observed. Overall, the number of Hox gene clusters has been regarded as a reliable marker of ploidy levels in animal genomes. In fact, this scheme also fits the situations in teleost fishes that experienced an additional WGD. In this review, I focus on cyclostomes and cartilaginous fishes as lineages that would fill the gap between invertebrates and osteichthyans. A recent study highlighted a possible loss of the HoxC cluster in the galeomorph shark lineage, while other aspects of cartilaginous fish Hox clusters usually mark their conserved nature. In contrast, existing resources suggest that the cyclostomes exhibit a different mode of Hox cluster organization. For this group of species, whose genomes could have differently responded to the 2R-WGDs from jawed vertebrates, therefore the number of Hox clusters may not serve as a good indicator of their ploidy level.
基金supported by the Major State Basic Research Development Program of China(973 Program) (Grant No.2010CB126603)the National Natural Science Foundation of China(No.30570172)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘Whole genome duplication （WGD） events have been proven to occur in the evolutionary history of most angiosperms. Tomato is considered a model species of the Solanaceae family. In this study, we describe the details of the evolutionary process of the tomato genome by detecting collinearity blocks and dating the WGD events on the tree of life by combining two different methods： synonymous substitution rates （Ks） and phylogenetic trees. In total, 593 collinearity blocks were discovered out of 12 pseudo-chromosomes con- structed. It was evident that chromosome 2 had experienced an intra-chromosomat duplication event. Major inter-chromosomal dupli- cation occurred among all the pseudo-chromosome. We calculated the Ks value of these collinearity blocks. Two peaks of Ks distribution were found, corresponding to two WGD events occurring approximately 36-82 million years ago （MYA） and 148--205 MYA. Additionally, the results of phylogenetic trees suggested that the more recent WGD event may have occurred after the divergence of the rosidasterid clade, but before the major diversification in Solanaceae. The older WGD event was shown to have occurred before the divergence of the rosid-asterid clade and after the divergence of rice-Arabidopsis （monocot-dicot）.
基金Supported by the National Natural Science Foundation of China(32072883,31802183)Conversion Project of Scientific and Technological Achievements of Zhejiang Academy of Agricultural Sciences(2020R22CB001).
