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Harnessing genetic diversity in major staple crops through the development of new breeding capabilities is essential to ensure food security1. Here we examined the genetic and phenotypic diversity of the A. E. Watkins landrace collection2 of bread wheat (Triticum aestivum), a major global cereal, by whole-genome re-sequencing of 827 Watkins landraces and 208 modern cultivars and in-depth field evaluation spanning a decade. We found that modern cultivars are derived from two of the seven ancestral groups of wheat and maintain very long-range haplotype integrity. The remaining five groups represent untapped genetic sources, providing access to landrace-specific alleles and haplotypes for breeding. Linkage disequilibrium-based haplotypes and association genetics analyses link Watkins genomes to the thousands of identified high-resolution quantitative trait loci and significant marker-trait associations. Using these structured germplasm, genotyping and informatics resources, we revealed many Watkins-unique beneficial haplotypes that can confer superior traits in modern wheat. Furthermore, we assessed the phenotypic effects of 44,338 Watkins-unique haplotypes, introgressed from 143 prioritized quantitative trait loci in the context of modern cultivars, bridging the gap between landrace diversity and current breeding. This study establishes a framework for systematically utilizing genetic diversity in crop improvement to achieve sustainable food security.
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Variação Genética , Genoma de Planta , Haplótipos , Desequilíbrio de Ligação , Fenótipo , Melhoramento Vegetal , Locos de Características Quantitativas , Triticum , Triticum/genética , Haplótipos/genética , Locos de Características Quantitativas/genética , Desequilíbrio de Ligação/genética , Variação Genética/genética , Genoma de Planta/genética , Alelos , Produtos Agrícolas/genética , Introgressão Genética , Sequenciamento Completo do GenomaRESUMO
Lake Untersee, a lake in Antarctica that is perennially covered with ice, is home to unique microbial structures that are not lithified. We have evaluated the structure of the community and its metabolic potential across the pigmented upper layers and the sediment-enriched deeper layers in these pinnacle and cone-shaped microbial structures using metagenomics. These microbial structures are inhabited by distinct communities. The upper layers of the cone-shaped structures have a higher abundance of the cyanobacterial MAG Microcoleus, while the pinnacle-shaped structures have a higher abundance of Elainellacea MAG. This suggests that cyanobacteria influence the morphologies of the mats. We identified stark contrasts in the composition of the community and its metabolic potential between the upper and lower layers of the mat. The upper layers of the mat, which receive light, have an increased abundance of photosynthetic pathways. In contrast, the lower layer has an increased abundance of heterotrophic pathways. Our results also showed that Lake Untersee is the first Antarctic lake with a substantial presence of ammonia-oxidizing Nitrospiracea and amoA genes. The genomic capacity for recycling biological molecules was prevalent across metagenome-assembled genomes (MAGs) that cover 19 phyla. This highlights the importance of nutrient scavenging in ultra-oligotrophic environments. Overall, our study provides new insights into the formation of microbial structures and the potential metabolic complexity of Antarctic laminated microbial mats. These mats are important environments for biodiversity that drives biogeochemical cycling in polar deserts.
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Bactérias , Cianobactérias , Lagos , Metagenômica , Regiões Antárticas , Lagos/microbiologia , Bactérias/genética , Bactérias/classificação , Bactérias/metabolismo , Cianobactérias/genética , Cianobactérias/classificação , Cianobactérias/metabolismo , Microbiota/genética , Filogenia , Sedimentos Geológicos/microbiologia , Metagenoma , Genoma Bacteriano , Archaea/genética , Archaea/classificação , Archaea/metabolismoRESUMO
High-throughput genotyping arrays have provided a cost-effective, reliable and interoperable system for genotyping hexaploid wheat and its relatives. Existing, highly cited arrays including our 35K Wheat Breeder's array and the Illumina 90K array were designed based on a limited amount of varietal sequence diversity and with imperfect knowledge of SNP positions. Recent progress in wheat sequencing has given us access to a vast pool of SNP diversity, whilst technological improvements have allowed us to fit significantly more probes onto a 384-well format Axiom array than previously possible. Here we describe a novel Axiom genotyping array, the 'Triticum aestivum Next Generation' array (TaNG), largely derived from whole genome skim sequencing of 204 elite wheat lines and 111 wheat landraces taken from the Watkins 'Core Collection'. We used a novel haplotype optimization approach to select SNPs with the highest combined varietal discrimination and a design iteration step to test and replace SNPs which failed to convert to reliable markers. The final design with 43 372 SNPs contains a combination of haplotype-optimized novel SNPs and legacy cross-platform markers. We show that this design has an improved distribution of SNPs compared to previous arrays and can be used to generate genetic maps with a significantly higher number of distinct bins than our previous array. We also demonstrate the improved performance of TaNGv1.1 for Genome-wide association studies (GWAS) and its utility for Copy Number Variation (CNV) analysis. The array is commercially available with supporting marker annotations and initial genotyping results freely available.
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Técnicas de Genotipagem , Polimorfismo de Nucleotídeo Único , Triticum , Triticum/genética , Polimorfismo de Nucleotídeo Único/genética , Técnicas de Genotipagem/métodos , Genoma de Planta/genética , Haplótipos/genética , Genótipo , Análise de Sequência com Séries de OligonucleotídeosRESUMO
Background: Programmes that work with parents to build couple relationship and parenting skills and include critical reflection on gender norms are a promising approach for reducing violence against women and children. However, there is limited evidence of their longer-term impact. In Rwanda, the Bandebereho programme engaged expectant and current parents of children under five years. At 21-months, Bandebereho demonstrated positive impacts on intimate partner violence (IPV), child physical punishment, maternal health-seeking, and couple relations. This study seeks to explore whether those outcomes are sustained six years later. Methods: A six-year follow-up to a two-arm, multi-site randomised controlled trial was conducted in four districts of Rwanda between May and September 2021. At baseline, couples were randomly assigned to either the 15-session intervention (n = 575) or a control group (n = 624). At this follow-up, 1003 men and 1021 women were included in intention to treat analysis. Generalised estimating equations with robust standard errors were used to fit the models. This study was registered with Clinicaltrials.gov (NCT04861870). Findings: Bandebereho has lasting effects on IPV and physical punishment of children, alongside multiple health and relationship outcomes. Compared to the control group: intervention women report less past-year physical (OR = 0.45, 95% CI 0.34-0.60 p < 0.001), sexual (OR = 0.50, 95% CI 0.37-0.67, p < 0.001), economic (OR = 0.47 95% CI 0.34-0.64, p < 0.001), and moderate or severe emotional (OR = 0.40 95% CI 0.29-0.56, p < 0.001) IPV. Intervention couples report less child physical punishment (OR = 0.72, p = 0.009 for men; OR = 0.68, p = 0.017 for women), fewer depressive symptoms (OR = 0.52, p < 0.001 for men; OR = 0.50, p < 0.001 for women), less harmful alcohol use, and improved maternal health-seeking, father engagement, and division of household labour and decision-making. Interpretation: Our study expands the evidence, demonstrating that programmes engaging men and women to promote collaborative and non-violent couple relations can result in sustained reductions in family violence six years later. Funding: The Echidna Giving Fund, Grand Challenges Canada, the Oak Foundation, and Wellspring Philanthropic Fund supported this study.
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Engaging adolescent males is a promising violence prevention strategy. This study explored primary versus secondary prevention effects of a gender-transformative program (i.e., Manhood 2.0) versus job-readiness training on multiple forms of violence perpetration. Adolescent males, ages 13 to 19 years, were recruited through youth-serving organizations in Pittsburgh, PA, between July 27, 2015, and June 5, 2017, to participate in an unblinded community-based cluster-randomized trial in 20 neighborhoods. The intervention curriculum, Manhood 2.0, focused on challenging norms that foster gender-based violence and building bystander skills. The control program was job-readiness training. We completed a planned secondary analysis of surveys from baseline and 9 months post intervention (follow-up), wherein we stratified participants based on any sexual violence/adolescent relationship abuse (SV/ARA) at baseline and examined risk of perpetration of SV/ARA, incapacitated sex, sexual harassment, cyber sexual abuse, peer violence, bullying, and homophobic teasing at follow-up. Among 866 participants, mean age was 15.6 years, 70% identified as Black, 6% as Hispanic, and 6% as multiracial. In both the Manhood 2.0 intervention group and job-readiness control groups, youth who reported SV/ARA at baseline were significantly more likely to report any form of SV/ARA, incapacitated sex, sexual harassment, cyber sexual abuse, bullying, and homophobic teasing at follow-up. Among participants who reported no SV/ARA perpetration at baseline, participating in the Manhood 2.0 intervention program was associated with increased risk of SV/ARA at follow-up compared to participating in the job-readiness control program. Among participants who reported SV/ARA perpetration at baseline, participating in the Manhood 2.0 intervention group was associated with lower risk of peer violence at follow-up. Synergizing gender-transformative approaches with job-readiness training may offer opportunities for crosscutting prevention programming to address multiple forms of violence.
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Delitos Sexuais , Assédio Sexual , Humanos , Masculino , Adolescente , Prevenção Secundária , Delitos Sexuais/prevenção & controle , Assédio Sexual/prevenção & controle , Violência/prevenção & controle , Grupo AssociadoRESUMO
Over the past decade, there has been rapid growth in the evidence for programs to prevent or reduce intimate partner violence (IPV)-the most common form of men's violence against women. IPV interventions targeting heterosexual couples have shown significant impact. However, our understanding of how these interventions achieve their impacts on violence-the mechanisms through which change occurs-remains limited. Using data from two follow-up rounds of a randomized controlled trial of the Bandebereho intervention in Rwanda, we constructed conceptually driven structural equation models to represent the processes by which hypothesized mediating variables linked treatment assignment to IPV. We found significant differences in the expected direction between the intervention and control participants on all mediating variables, including men's alcohol use, communication frequency, emotional closeness, frequency of quarreling, and men's attitudes related to gender and violence. Several mechanisms-more positive couple dynamics including emotional closeness and communication frequency; men's gender-equitable attitudes; men's alcohol use-accounted for the largest proportions of the effect of assignment to the Bandebereho intervention on IPV. Overall, our findings highlight that no one particular component is driving the reductions in violence; instead, the multiple components and pathways account for the intervention's effects, suggesting that the holistic nature of the intervention may be integral to its positive impact. The Bandebereho trial from which data was used in this analysis was registered on ClinicalTrials.gov prior to completion ( NCT02694627 ).
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Alcoolismo , Violência por Parceiro Íntimo , Masculino , Humanos , Feminino , Alcoolismo/prevenção & controle , Ruanda , Violência por Parceiro Íntimo/prevenção & controle , Violência por Parceiro Íntimo/psicologia , Identidade de Gênero , Consumo de Bebidas AlcoólicasRESUMO
The bread wheat (Triticum aestivum) pangenome is a patchwork of variable regions, including translocations and introgressions from progenitors and wild relatives. Although a large number of these have been documented, it is likely that many more remain unknown. To map these variable regions and make them more traceable in breeding programs, wheat accessions need to be genotyped or sequenced. The wheat genome is large and complex and consequently, sequencing efforts are often targeted through exome capture. In this study, we employed exome capture prior to sequencing 12 wheat varieties; 10 elite T. aestivum cultivars and two T. aestivum landrace accessions. Sequence coverage across chromosomes was greater toward distal regions of chromosome arms and lower in centromeric regions, reflecting the capture probe distribution which itself is determined by the known telomere to centromere gene gradient. Superimposed on this general pattern, numerous drops in sequence coverage were observed. Several of these corresponded with reported introgressions. Other drops in coverage could not be readily explained and may point to introgressions that have not, to date, been documented.
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The CerealsDB website, created by members of the Functional Genomics Group at the University of Bristol, provides access to a database containing SNP and genotyping data for hexaploid wheat and, to a lesser extent, its progenitors and several of its relatives. The site is principally aimed at plant breeders and research scientists who wish to obtain information regarding SNP markers; for example, obtain primers used for their identification or the sequences upon which they are based. The database underpinning the website contains circa one million putative varietal SNPs of which several hundreds of thousands have been experimentally validated on a range of common genotyping platforms. For each SNP marker, the site also hosts the allelic scores for thousands of elite wheat varieties, landrace cultivars, and wheat relatives. Tools are available to help negotiate and visualize the datasets. The website has been designed to be simple and straightforward to use and is completely open access.
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Polimorfismo de Nucleotídeo Único , Genoma de Planta , Genômica , Triticum/genéticaRESUMO
East Africa is a hotspot for foodborne diseases, including infection by nontyphoidal Salmonella (NTS), a zoonotic pathogen that may originate from livestock. Urbanization and increased demand for animal protein drive intensification of livestock production and food processing, creating risks and opportunities for food safety. We built a probabilistic mathematical model, informed by prior beliefs and dedicated stakeholder interviews and microbiological research, to describe sources and prevalence of NTS along the beef supply chain in Moshi, Tanzania. The supply chain was conceptualized using a bow tie model, with terminal livestock markets as pinch point, and a forked pathway postmarket to compare traditional and emerging supply chains. NTS was detected in 36 (7.7%) of 467 samples throughout the supply chain. After combining prior belief and observational data, marginal estimates of true NTS prevalence were 4% in feces of cattle entering the beef supply and 20% in raw meat at butcheries. Based on our model and sensitivity analyses, true NTS prevalence was not significantly different between supply chains. Environmental contamination, associated with butchers and vendors, was estimated to be the most likely source of NTS in meat for human consumption. The model provides a framework for assessing the origin and propagation of NTS along meat supply chains. It can be used to inform decision making when economic factors cause changes in beef production and consumption, such as where to target interventions to reduce risks to consumers. Through sensitivity and value of information analyses, the model also helps to prioritize investment in additional research.
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Carne , Salmonella , Animais , Bovinos , Gado , Carne/microbiologia , Modelos Estatísticos , TanzâniaRESUMO
The Arctic environment is particularly affected by global warming, and a clear trend of the ice retreat is observed worldwide. In proglacial systems, the newly exposed terrain represents different environmental and nutrient conditions compared to later soil stages. Therefore, proglacial systems show several environmental gradients along the soil succession where microorganisms are active protagonists of the soil and carbon pool formation through nitrogen fixation and rock weathering. We studied the microbial succession of three Arctic proglacial systems located in Svalbard (Midtre Lovénbreen), Sweden (Storglaciären), and Greenland (foreland close to Kangerlussuaq). We analyzed 65 whole shotgun metagenomic soil samples for a total of more than 400 Gb of sequencing data. Microbial succession showed common trends typical of proglacial systems with increasing diversity observed along the forefield chronosequence. Microbial trends were explained by the distance from the ice edge in the Midtre Lovénbreen and Storglaciären forefields and by total nitrogen (TN) and total organic carbon (TOC) in the Greenland proglacial system. Furthermore, we focused specifically on genes associated with nitrogen fixation and biotic rock weathering processes, such as nitrogenase genes, obcA genes, and genes involved in cyanide and siderophore synthesis and transport. Whereas we confirmed the presence of these genes in known nitrogen-fixing and/or rock weathering organisms (e.g., Nostoc, Burkholderia), in this study, we also detected organisms that, even if often found in soil and proglacial systems, have never been related to nitrogen-fixing or rock weathering processes before (e.g., Fimbriiglobus, Streptomyces). The different genera showed different gene trends within and among the studied systems, indicating a community constituted by a plurality of organisms involved in nitrogen fixation and biotic rock weathering, and where the latter were driven by different organisms at different soil succession stages.
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Permafrost represents a reservoir for the biodiscovery of cold-adapted proteins which are advantageous in industrial and medical settings. Comparisons between different thermo-adapted proteins can give important information for cold-adaptation bioengineering. We collected permafrost active layer samples from 34 points along a proglacial transect in southwest Greenland. We obtained a deep read coverage assembly (>164x) from nanopore and Illumina sequences for the purposes of i) analysing metagenomic and metatranscriptomic trends of the microbial community of this area, and ii) creating the Cold-Adapted Predicted Protein (CAPP) database. The community showed a similar taxonomic composition in all samples along the transect, with a solid permafrost-shaped community, rather than microbial trends typical of proglacial systems. We retrieved 69 high- and medium-quality metagenome-assembled clusters, 213 complete biosynthetic gene clusters and more than three million predicted proteins. The latter constitute the CAPP database that can provide cold-adapted protein sequence information for protein- and taxon-focused amino acid sequence modifications for the future bioengineering of cold-adapted enzymes. As an example, we focused on the enzyme polyphenol oxidase, and demonstrated how sequence variation information could inform its protein engineering.
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Pergelissolo , Groenlândia , Metagenoma , Metagenômica , Microbiologia do SoloRESUMO
Many environmental and biomedical biomonitoring and detection studies aim to explore the presence of specific organisms or gene functionalities in microbiome samples. In such cases, when the study hypotheses can be answered with the exploration of a small number of genes, a targeted PCR-approach is appropriate. However, due to the complexity of environmental microbial communities, the design of specific primers is challenging and can lead to non-specific results. We designed PhyloPrimer, the first user-friendly platform to semi-automate the design of taxon-specific oligos (i.e., PCR primers) for a gene of interest. The main strength of PhyloPrimer is the ability to retrieve and align GenBank gene sequences matching the user's input, and to explore their relationships through an online dynamic tree. PhyloPrimer then designs oligos specific to the gene sequences selected from the tree and uses the tree non-selected sequences to look for and maximize oligo differences between targeted and non-targeted sequences, therefore increasing oligo taxon-specificity (positive/negative consensus approach). Designed oligos are then checked for the presence of secondary structure with the nearest-neighbor (NN) calculation and the presence of off-target matches with in silico PCR tests, also processing oligos with degenerate bases. Whilst the main function of PhyloPrimer is the design of taxon-specific oligos (down to the species level), the software can also be used for designing oligos to target a gene without any taxonomic specificity, for designing oligos from preselected sequences and for checking predesigned oligos. We validated the pipeline on four commercially available microbial mock communities using PhyloPrimer to design genus- and species-specific primers for the detection of Streptococcus species in the mock communities. The software performed well on these mock microbial communities and can be found at https://www.cerealsdb.uk.net/cerealgenomics/phyloprimer.
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Bread wheat (Triticum aestivum) is one of the world's most important crops; however, a low level of genetic diversity within commercial breeding accessions can significantly limit breeding potential. In contrast, wheat relatives exhibit considerable genetic variation and so potentially provide a valuable source of novel alleles for use in breeding new cultivars. Historically, gene flow between wheat and its relatives may have contributed novel alleles to the bread wheat pangenome. To assess the contribution made by wheat relatives to genetic diversity in bread wheat, we used markers based on single nucleotide polymorphisms to compare bread wheat accessions, created in the past 150 years, with 45 related species. We show that many bread wheat accessions share near-identical haplotype blocks with close relatives of wheat's diploid and tetraploid progenitors, while some show evidence of introgressions from more distant species and structural variation between accessions. Hence, introgressions and chromosomal rearrangements appear to have made a major contribution to genetic diversity in cultivar collections. As gene flow from relatives to bread wheat is an ongoing process, we assess the impact that introgressions might have on future breeding strategies.
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Pão , Instabilidade Cromossômica , Fluxo Gênico , Genoma de Planta , Melhoramento Vegetal/métodos , Triticum/genética , Variação Genética , Genótipo , Polimorfismo de Nucleotídeo ÚnicoRESUMO
Tracking genetic variations from positive SARS-CoV-2 samples yields crucial information about the number of variants circulating in an outbreak and the possible lines of transmission but sequencing every positive SARS-CoV-2 sample would be prohibitively costly for population-scale test and trace operations. Genotyping is a rapid, high-throughput and low-cost alternative for screening positive SARS-CoV-2 samples in many settings. We have designed a SNP identification pipeline to identify genetic variation using sequenced SARS-CoV-2 samples. Our pipeline identifies a minimal marker panel that can define distinct genotypes. To evaluate the system, we developed a genotyping panel to detect variants-identified from SARS-CoV-2 sequences surveyed between March and May 2020 and tested this on 50 stored qRT-PCR positive SARS-CoV-2 clinical samples that had been collected across the South West of the UK in April 2020. The 50 samples split into 15 distinct genotypes and there was a 61.9% probability that any two randomly chosen samples from our set of 50 would have a distinct genotype. In a high throughput laboratory, qRT-PCR positive samples pooled into 384-well plates could be screened with a marker panel at a cost of < £1.50 per sample. Our results demonstrate the usefulness of a SNP genotyping panel to provide a rapid, cost-effective, and reliable way to monitor SARS-CoV-2 variants circulating in an outbreak. Our analysis pipeline is publicly available and will allow for marker panels to be updated periodically as viral genotypes arise or disappear from circulation.
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COVID-19/virologia , Técnicas de Genotipagem/métodos , SARS-CoV-2/genética , SARS-CoV-2/isolamento & purificação , COVID-19/diagnóstico , COVID-19/epidemiologia , Variação Genética , Humanos , Pandemias , Polimorfismo de Nucleotídeo Único , Reino Unido/epidemiologiaRESUMO
Free asparagine is the precursor for acrylamide, which forms during the baking, toasting and high-temperature processing of foods made from wheat. In this study, CRISPR/Cas9 was used to knock out the asparagine synthetase gene, TaASN2, of wheat (Triticum aestivum) cv. Cadenza. A 4-gRNA polycistronic gene was introduced into wheat embryos by particle bombardment and plants were regenerated. T1 plants derived from 11 of 14 T0 plants were shown to carry edits. Most edits were deletions (up to 173 base pairs), but there were also some single base pair insertions and substitutions. Editing continued beyond the T1 generation. Free asparagine concentrations in the grain of plants carrying edits in all six TaASN2 alleles (both alleles in each genome) were substantially reduced compared with wildtype, with one plant showing a more than 90 % reduction in the T2 seeds. A plant containing edits only in the A genome alleles showed a smaller reduction in free asparagine concentration in the grain, but the concentration was still lower than in wildtype. Free asparagine concentration in the edited plants was also reduced as a proportion of the free amino acid pool. Free asparagine concentration in the T3 seeds remained substantially lower in the edited lines than wildtype, although it was higher than in the T2 seeds, possibly due to stress. In contrast, the concentrations of free glutamine, glutamate and aspartate were all higher in the edited lines than wildtype. Low asparagine seeds showed poor germination but this could be overcome by exogenous application of asparagine.
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Aspartato-Amônia Ligase , Triticum , Asparagina/metabolismo , Aspartato-Amônia Ligase/genética , Sistemas CRISPR-Cas/genética , Grão Comestível/metabolismo , Edição de Genes , Triticum/genética , Triticum/metabolismoRESUMO
Antarctic perennially ice-covered lakes provide a stable low-disturbance environment where complex microbially mediated structures can grow. Lake Untersee, an ultra-oligotrophic lake in East Antarctica, has the lake floor covered in benthic microbial mat communities, where laminated organo-sedimentary structures form with three distinct, sympatric morphologies: small, elongated cuspate pinnacles, large complex cones and flat mats. We examined the diversity of prokaryotes and eukaryotes in pinnacles, cones and flat microbial mats using high-throughput sequencing of 16S and 18S rRNA genes and assessed how microbial composition may underpin the formation of these distinct macroscopic mat morphologies under the same environmental conditions. Our analysis identified distinct clustering of microbial communities according to mat morphology. The prokaryotic communities were dominated by Cyanobacteria, Proteobacteria, Verrucomicrobia, Planctomycetes, and Actinobacteria. While filamentous Tychonema cyanobacteria were common in all mat types, Leptolyngbya showed an increased relative abundance in the pinnacle structures only. Our study provides the first report of the eukaryotic community structure of Lake Untersee benthic mats, which was dominated by Ciliophora, Chlorophyta, Fungi, Cercozoa, and Discicristata. The eukaryote richness was lower than for prokaryote assemblages and no distinct clustering was observed between mat morphologies. These findings suggest that cyanobacterial assemblages and potentially other bacteria and eukaryotes may influence structure morphogenesis, allowing distinct structures to form across a small spatial scale.
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Accurate identification of named accessions in germplasm collections is extremely important, especially for vegetatively propagated crops which are expensive to maintain. Thus, an inexpensive, reliable, and rapid genotyping method is essential because it avoids the need for laborious and time-consuming morphological comparisons. Single Nucleotide Polymorphism (SNP) marker panels containing large numbers of SNPs have been developed for many crop species, but such panels are much too large for basic cultivar identification. Here, we have identified a minimum set of SNP markers sufficient to distinguish apple cultivars held in the English and Welsh national collections providing a cheaper and automatable alternative to the markers currently used by the community. We show that SNP genotyping with a small set of well selected markers is equally efficient as microsatellites for the identification of apple cultivars and has the added advantage of automation and reduced cost when screening large numbers of samples.
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Genoma de Planta/genética , Malus/genética , Repetições de Microssatélites/genética , Polimorfismo de Nucleotídeo Único/genética , Alelos , Cruzamento , Produtos Agrícolas/genética , Genótipo , Humanos , Malus/classificação , Banco de Sementes/classificaçãoRESUMO
Bacteriophage genomes rapidly evolve via mutation and horizontal gene transfer to counter evolving bacterial host defenses; such arms race dynamics should lead to divergence between phages from similar, geographically isolated ecosystems. However, near-identical phage genomes can reoccur over large geographical distances and several years apart, conversely suggesting many are stably maintained. Here, we show that phages with near-identical core genomes in distant, discrete aquatic ecosystems maintain diversity by possession of numerous flexible gene modules, where homologous genes present in the pan-genome interchange to create new phage variants. By repeatedly reconstructing the core and flexible regions of phage genomes from different metagenomes, we show a pool of homologous gene variants co-exist for each module in each location, however, the dominant variant shuffles independently in each module. These results suggest that in a natural community, recombination is the largest contributor to phage diversity, allowing a variety of host recognition receptors and genes to counter bacterial defenses to co-exist for each phage.
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Bacteriófagos/genética , Camada de Gelo/virologia , Metagenoma , Cianobactérias/virologia , Ecossistema , Transferência Genética Horizontal , Genes Virais , Genoma Viral , Interações entre Hospedeiro e Microrganismos/genética , Camada de Gelo/microbiologia , Metagenômica , FilogeniaRESUMO
CerealsDB (www.cerealsdb.uk.net) is an online repository of mainly hexaploid wheat (Triticum aestivum) single nucleotide polymorphisms (SNPs) and genotyping data. The CerealsDB website has been designed to enable wheat breeders and scientists to select the appropriate markers for research breeding tasks, such as marker-assisted selection. We report a large update of genotyping information for over 6000 wheat accessions and describe new webtools for exploring and visualizing the data. We also describe a new database of quantitative trait loci that links phenotypic traits to CerealsDB SNP markers and allelic scores for each of those markers. CerealsDB is an open-access website that hosts information on wheat SNPs considered useful for both plant breeders and research scientists. The latest CerealsDB database is available at https://www.cerealsdb.uk.net/cerealgenomics/CerealsDB/indexNEW.php.