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How do you explain flaw in a world engineered by God? Avise extends this age-old question to the most basic aspect of humanity's physical evidence-- our genes-- and provides the evolutionary answers.

Research in the past decade has demonstrated that a single reference genome is not representative of a species’ diversity. MaizeGDB introduces a pan-genomic approach to hosting genomic data, leveraging the large number of diverse maize genomes and their associated datasets to quickly and efficiently connect genomes, gene models, expression, epigenome, sequence variation, structural variation, transposable elements, and diversity data across genomes so that researchers can easily track the structural and functional differences of a locus and its orthologs across maize. We believe our framework is unique and provides a template for any genomic database poised to host large-scale pan-genomic data.

Background Cucumber ( Cucumis sativus L.) is an economically important vegetable crop species. However, it is susceptible to various abiotic and biotic stresses. WRKY transcription factors play important roles in plant growth and development, particularly in the plant response to biotic and abiotic stresses. However, little is known about the expression pattern of WRKY genes under different stresses in cucumber. Results In the present study, an analysis of the new assembly of the cucumber genome (v3.0) allowed the identification of 61 cucumber WRKY genes. Phylogenetic and synteny analyses were performed using related species to investigate the evolution of the cucumber WRKY genes. The 61 CsWRKYs were classified into three main groups, within which the gene structure and motif compositions were conserved. Tissue expression profiles of the WRKY genes demonstrated that 24 CsWRKY genes showed constitutive expression (FPKM > 1 in all samples), and some WRKY genes showed organ-specific expression, suggesting that these WRKYs might be important for plant growth and organ development in cucumber. Importantly, analysis of the CsWRKY gene expression patterns revealed that five CsWRKY genes strongly responded to both salt and heat stresses, 12 genes were observed to be expressed in response to infection from downy mildew and powdery mildew, and three CsWRKY genes simultaneously responded to all treatments analysed. Some CsWRKY genes were observed to be induced/repressed at different times after abiotic or biotic stress treatment, demonstrating that cucumber WRKY genes might play different roles during different stress responses and that their expression patterns vary in response to stresses. Conclusions Sixty-one WRKY genes were identified in cucumber, and insight into their classification, evolution, and expression patterns was gained in this study. Responses to different abiotic and biotic stresses in cucumber were also investigated. Our results provide a better understanding of the function of CsWRKY genes in improving abiotic and biotic stress resistance in cucumber.

Background Oat ( Avena sativa L.) is a recognized health-food, and the contributions of its different candidate A-genome progenitor species remain inconclusive. Here, we report chloroplast genome sequences of eleven Avena species, to examine the plastome evolutionary dynamics and analyze phylogenetic relationships between oat and its congeneric wild related species. Results The chloroplast genomes of eleven Avena species (size range of 135,889–135,998 bp) share quadripartite structure, comprising of a large single copy (LSC; 80,014–80,132 bp), a small single copy (SSC; 12,575–12,679 bp) and a pair of inverted repeats (IRs; 21,603–21,614 bp). The plastomes contain 131 genes including 84 protein-coding genes, eight ribosomal RNAs and 39 transfer RNAs. The nucleotide sequence diversities (Pi values) range from 0.0036 ( rps19 ) to 0.0093 ( rpl32 ) for ten most polymorphic genes and from 0.0084 ( psbH-petB ) to 0.0240 ( petG-trnW-CCA ) for ten most polymorphic intergenic regions. Gene selective pressure analysis shows that all protein-coding genes have been under purifying selection. The adjacent position relationships between tandem repeats, insertions/deletions and single nucleotide polymorphisms support the evolutionary importance of tandem repeats in causing plastome mutations in Avena . Phylogenomic analyses, based on the complete plastome sequences and the LSC intermolecular recombination sequences, support the monophyly of Avena with two clades in the genus. Conclusions Diversification of Avena plastomes is explained by the presence of highly diverse genes and intergenic regions, LSC intermolecular recombination, and the co-occurrence of tandem repeat and indels or single nucleotide polymorphisms. The study demonstrates that the A-genome diploid-polyploid lineage maintains two subclades derived from different maternal ancestors, with A. longiglumis as the first diverging species in clade I. These genome resources will be helpful in elucidating the chloroplast genome structure, understanding the evolutionary dynamics at genus Avena and family Poaceae levels, and are potentially useful to exploit plastome variation in making hybrids for plant breeding.

Background The cytochrome P450s (CYP450s) as the largest enzyme family of plant metabolism participate in various physiological processes, whereas no study has demonstrated interest in comprehensive comparison of the genes in wheat and maize. Genome-wide survey, characterization and comparison of wheat and maize CYP450 gene superfamily are useful for genetic manipulation of the Gramineae crops. Results In total, 1285 and 263 full-length CYP450 s were identified in wheat and maize, respectively. According to standard nomenclature, wheat CYP450 s ( TaCYP450 s) were categorized into 45 families, while maize CYP450 s ( ZmCYP450 s) into 43 families. A comprehensive analysis of wheat and maize CYP450s, involved in functional domains, conserved motifs, phylogeny, gene structures, chromosome locations and duplicated events was performed. The result showed that each family/subfamily in both species exhibited characteristic features, suggesting their phylogenetic relationship and the potential divergence in their functions. Functional divergence analysis at the amino acid level of representative clans CYP51, CYP74 and CYP97 in wheat, maize and rice identified some critical amino acid sites that are responsible for functional divergence of a gene family. Expression profiles of Ta -, ZmCYP450 s were investigated using RNA-seq data, which contribute to infer the potential functions of the genes during development and stress responses. We found in both species CYP450 s had preferential expression in specific tissues, and many tissue-specific genes were identified. Under water-deficit condition, 82 and 39 significantly differentially expressed CYP450 s were respectively detected in wheat and maize. These genes may have some roles in protecting plants against drought damage. Thereinto, fourteen CYP450s were selected to validate their expression level through qRT-PCR. To further elucidating molecular mechanisms of CYP450 action, gene co-expression network was constructed. In total, 477 TaCYP450 s were distributed in 22 co-expression modules, and some co-expressed genes that likely take part in the same biochemical pathway were identified. For instance, the expression of TaCYP74A98_4D was highly correlated with TaLOX9 , TaLOX36 , TaLOX39 , TaLOX44 and TaOPR8 , and all of them may be involved in jasmonate (JA) biosynthesis. TaCYP73A201_3A showed coexpression with TaPAL1.25 , TaCCoAOMT1.2 , TaCOMT.1 , TaCCR1.6 and TaLAC5 , which probably act in the wheat stem and/or root lignin synthesis pathway. Conclusion Our study first established systematic information about evolutionary relationship, expression pattern and function characterization of CYP450 s in wheat and maize.

Background Cotton ( Gossypium spp.) is the most important fiber and oil crop in the world. With the emergence of huge -omics data sets, it is essential to have an integrated functional genomics database that allows worldwide users to quickly and easily fetch and visualize genomic information. Currently available cotton-related databases have some weakness in integrating multiple kinds of -omics data from multiple Gossypium species. Therefore, it is necessary to establish an integrated functional genomics database for cotton. Description We developed CottonFGD (Cotton Functional Genomic Database, https://cottonfgd.org ), an integrated database that includes genomic sequences, gene structural and functional annotations, genetic marker data, transcriptome data, and population genome resequencing data for all four of the sequenced Gossypium species. It consists of three interconnected modules: search, profile, and analysis. These modules make CottonFGD enable both single gene review and batch analysis with multiple kinds of -omics data and multiple species. CottonFGD also includes additional pages for data statistics, bulk data download, and a detailed user manual. Conclusion Equipped with specialized functional modules and modernized visualization tools, and populated with multiple kinds of -omics data, CottonFGD provides a quick and easy-to-use data analysis platform for cotton researchers worldwide.

Background Lythraceae belongs to the order Myrtales, which is part of Archichlamydeae. The family has 31 genera containing approximately 620 species of herbs, shrubs and trees. Of these 31 genera, five large genera each possess 35 or more species. They are Lythrum , with 35; Rotala , with 45; Nesaea , with 50; Lagerstroemia , with 56; and Cuphea , with 275 species. Results We reported six newly sequenced chloroplast (cp) genomes ( Duabanga grandiflora , Trapa natans , Lythrum salicaria , Lawsonia inermis , Woodfordia fruticosa and Rotala rotundifolia ) and compared them with 16 other cp genomes of Lythraceae species. The cp genomes of the 22 Lythraceae species ranged in length from 152,049 bp to 160,769 bp. In each Lythraceae species, the cp genome contained 112 genes consisting of 78 protein coding genes, four ribosomal RNAs and 30 transfer RNAs. Furthermore, we detected 211–332 simple sequence repeats (SSRs) in six categories and 7–27 long repeats in four categories. We selected ten divergent hotspots ( ndhF, matK, ycf1, rpl22, rpl32, trnK-rps16, trnR-atpA, rpl32-trnL, trnH-psbA and trnG-trnR ) among the 22 Lythraceae species to be potential molecular markers. We constructed phylogenetic trees from 42 Myrtales plants with 8 Geraniales plants as out groups. The relationships among the Myrtales species were effectively distinguished by maximum likelihood (ML), maximum parsimony (MP) and Bayesian inference (BI) trees constructed using 66 protein coding genes. Generally, the 22 Lythraceae species gathered into one clade, which was resolved as sister to the three Onagraceae species. Compared with Melastomataceae and Myrtaceae, Lythraceae and Onagraceae differentiated later within Myrtales. Conclusions The study provided ten potential molecular markers as candidate DNA barcodes and contributed cp genome resources within Myrtales for further study.

Background In plants, the basic helix-loop-helix (bHLH) transcription factors play key roles in diverse biological processes. Genome-wide comprehensive and systematic analyses of bHLH proteins have been well conducted in Arabidopsis , rice, tomato and other plant species. However, only few of bHLH family genes have been functional characterized in maize. Results In this study, our genome-wide analysis identified 208 putative bHLH family proteins (ZmbHLH proteins) in maize ( Zea mays ). We classified these proteins into 18 subfamilies by comparing the ZmbHLHs with Arabidopsis thaliana bHLH proteins. Phylogenetic analysis, conserved protein motifs, and exon-intron patterns further supported the evolutionary relationships among these bHLH proteins. Genome distribution analysis found that the 208 ZmbHLH loci were located non-randomly on the ten maize chromosomes. Further, analysis of conserved cis -elements in the promoter regions, protein interaction networks, and expression patterns in roots, leaves, and seeds across developmental stages, suggested that bHLH family proteins in maize are probably involved in multiple physiological processes in plant growth and development. Conclusion We performed a genome-wide, systematic analysis of bHLH proteins in maize. This comprehensive analysis provides a useful resource that enables further investigation of the physiological roles and molecular functions of the ZmbHLH transcription factors.

Background Pomelo is one of the three major species of citrus. The fruit accumulates a variety of abundant secondary metabolites that affect the flavor. UDP-glycosyltransferases (UGTs) are involved in the glycosylation of secondary metabolites. Results In the present study, we performed a genome-wide analysis of pomelo UGT family, a total of 145 UGTs was identified based on the conserved plant secondary product glycosyltransferase (PSPG) motif. These UGT genes were clustered into 16 major groups through phylogenetic analysis of these genes with other plant UGTs (A-P). Pomelo UGTs were distributed unevenly among the chromosomes. At least 10 intron insertion events were observed in these UGT genome sequences, and I-5 was identified to be the highest conserved one. The expression profile analysis of pomelo UGT genes in different fruit tissues during development and ripening was carried out by RNA-seq. Conclusions We identified 145 UGTs in pomelo fruit through transcriptome data and citrus genome database. Our research provides available information on UGTs studies in pomelo, and provides an important research foundation for screening and identification of functional UGT genes.

Background Auxin is critical to plant growth and development, as well as stress responses. Small auxin-up RNA ( SAUR ) is the largest family of early auxin responsive genes in higher plants. However, the function of few SAUR genes is known owing to functional redundancy among the many family members. Results In this study, we conducted a phylogenetic analysis using protein sequences of 795 SAURs from Anthoceros angustus , Marchantia polymorpha , Physcomitrella patens , Selaginella moellendorffii , Ginkgo biloba , Gnetum montanum , Amborella trichopoda , Arabidopsis thaliana , Oryza sativa , Zea mays , Glycine max , Medicago truncatula and Setaria italica . The phylogenetic trees showed that the SAUR proteins could be divided into 10 clades and three subfamilies, and that SAUR proteins of three bryophyte species were only located in subfamily III, which suggested that they may be ancestral. From bryophyta to anthophyta, SAUR family have appeared very large expansion. The number of SAUR gene in Fabaceae species was considerably higher than that in other plants, which may be associated with independent whole genome duplication event in the Fabaceae lineages. The phylogenetic trees also showed that SAUR genes had expanded independently monocotyledons and dicotyledons in angiosperms. Conserved motif and protein structure prediction revealed that SAUR proteins were highly conserved among higher plants, and two leucine residues in motif I were observed in almost all SAUR proteins, which suggests the residues plays a critical role in the stability and function of SAUR proteins. Expression analysis of SAUR genes using publicly available RNA-seq data from rice and soybean indicated functional similarity of members in the same clade, which was also further confirmed by qRT-PCR. Summarization of SAUR functions also showed that SAUR functions were usually consistent within a subclade. Conclusions This study provides insights into the evolution and function of the SAUR gene family from bryophyta to anthophyta, particularly in Fabaceae plants. Future investigation to understand the functions of SAUR family members should employ a clade as the study unit.