scholarly journals Eight soybean reference genome resources from varying latitudes and agronomic traits

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Jeffrey Shih-Chieh Chu ◽  
Bo Peng ◽  
Kuanqiang Tang ◽  
Xingxing Yi ◽  
Huangkai Zhou ◽  
...  
Keyword(s):  
De Novo ◽  
Agronomic Traits ◽  
Genomic Variation ◽  
Functional Studies ◽  
Technical Assessment ◽  
Genome Assemblies ◽  
Agronomical Traits ◽  
Multiple Reference ◽  
Reference Genomes

AbstractComparative analysis of multiple reference genomes representing diverse genetic backgrounds is critical for understanding the role of key alleles important in domestication and genetic breeding of important crops such as soybean. To enrich the genetic resources for soybean, we describe the generation, technical assessment, and preliminary genomic variation analysis of eight de novo reference-grade soybean genome assemblies from wild and cultivated accessions. These resources represent soybeans cultured at different latitudes and exhibiting different agronomical traits. Of these eight soybeans, five are from new accessions that have not been sequenced before. We demonstrate the usage of these genomes to identify small and large genomic variations affecting known genes as well as screening for genic PAV regions for identifying candidates for further functional studies.

scholarly journals Transposable elements contribute to dynamic genome content in maize

2019 ◽  
Author(s):  
Sarah N Anderson ◽  
Michelle C Stitzer ◽  
Alex B. Brohammer ◽  
Peng Zhou ◽  
Jaclyn M Noshay ◽  
...  
Keyword(s):  
Transposable Elements ◽  
Genomic Variation ◽  
Gene Content ◽  
Maize Genome ◽  
Large Scope ◽  
Shared Ancestry ◽  
Dynamic Genome ◽  
Genomic Studies ◽  
Genome Assemblies

AbstractTransposable elements (TEs) are ubiquitous components of eukaryotic genomes and can create variation in genomic organization. The majority of maize genomes are composed of TEs. We developed an approach to define shared and variable TE insertions across genome assemblies and applied this method to four maize genomes (B73, W22, Mo17, and PH207). Among these genomes we identified 1.6 Gb of variable TE sequence representing a combination of recent TE movement and deletion of previously existing TEs. Although recent TE movement only accounted for a portion of the TE variability, we identified 4,737 TEs unique to one genome with defined insertion sites in all other genomes. Variable TEs are found for all superfamilies and are distributed across the genome, including in regions of recent shared ancestry among individuals. There are 2,380 genes annotated in the B73 genome located within variable TEs, providing evidence for the role of TEs in contributing to the substantial differences in gene content among these genotypes. The large scope of TE variation present in this limited sample of temperate maize genomes highlights the major contribution of TEs in driving variation in genome organization and gene content.Significance StatementThe majority of the maize genome is comprised of transposable elements (TEs) that have the potential to create genomic variation within species. We developed a method to identify shared and non-shared TEs using whole genome assemblies of four maize inbred lines. Variable TEs are found throughout the maize genome and in comparisons of any two genomes we find ~20% of the genome is due to non-shared TEs. Several thousand maize genes are found within TEs that are variable across lines, highlighting the contribution of TEs to gene content variation. This study creates a comprehensive resource for genomic studies of TE variability among four maize genomes, which will enable studies on the consequences of variable TEs on genome function.

scholarly journals dnAQET: a framework to compute a consolidated metric for benchmarking quality of de novo assemblies

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Gokhan Yavas ◽  
Huixiao Hong ◽  
Wenming Xiao
Keyword(s):  
Quality Assessment ◽  
Genome Assembly ◽  
Reference Genome ◽  
De Novo ◽  
Quality Score ◽  
De Novo Genome Assembly ◽  
Genome Assemblies ◽  
Reference Genomes ◽  
Better Than

Abstract Background Accurate de novo genome assembly has become reality with the advancements in sequencing technology. With the ever-increasing number of de novo genome assembly tools, assessing the quality of assemblies has become of great importance in genome research. Although many quality metrics have been proposed and software tools for calculating those metrics have been developed, the existing tools do not produce a unified measure to reflect the overall quality of an assembly. Results To address this issue, we developed the de novo Assembly Quality Evaluation Tool (dnAQET) that generates a unified metric for benchmarking the quality assessment of assemblies. Our framework first calculates individual quality scores for the scaffolds/contigs of an assembly by aligning them to a reference genome. Next, it computes a quality score for the assembly using its overall reference genome coverage, the quality score distribution of its scaffolds and the redundancy identified in it. Using synthetic assemblies randomly generated from the latest human genome build, various builds of the reference genomes for five organisms and six de novo assemblies for sample NA24385, we tested dnAQET to assess its capability for benchmarking quality evaluation of genome assemblies. For synthetic data, our quality score increased with decreasing number of misassemblies and redundancy and increasing average contig length and coverage, as expected. For genome builds, dnAQET quality score calculated for a more recent reference genome was better than the score for an older version. To compare with some of the most frequently used measures, 13 other quality measures were calculated. The quality score from dnAQET was found to be better than all other measures in terms of consistency with the known quality of the reference genomes, indicating that dnAQET is reliable for benchmarking quality assessment of de novo genome assemblies. Conclusions The dnAQET is a scalable framework designed to evaluate a de novo genome assembly based on the aggregated quality of its scaffolds (or contigs). Our results demonstrated that dnAQET quality score is reliable for benchmarking quality assessment of genome assemblies. The dnQAET can help researchers to identify the most suitable assembly tools and to select high quality assemblies generated.

scholarly journals Merqury: reference-free quality, completeness, and phasing assessment for genome assemblies

2020 ◽  
Author(s):  
Arang Rhie ◽  
Brian P. Walenz ◽  
Sergey Koren ◽  
Adam M. Phillippy
Keyword(s):  
De Novo ◽  
High Accuracy ◽  
Link Type ◽  
Base Level ◽  
Project Home Page ◽  
Set Operations ◽  
Assembly Evaluation ◽  
Long Read ◽  
Genome Assemblies ◽  
Reference Genomes

AbstractRecent long-read assemblies often exceed the quality and completeness of available reference genomes, making validation challenging. Here we present Merqury, a novel tool for reference-free assembly evaluation based on efficient k-mer set operations. By comparing k-mers in a de novo assembly to those found in unassembled high-accuracy reads, Merqury estimates base-level accuracy and completeness. For trios, Merqury can also evaluate haplotype-specific accuracy, completeness, phase block continuity, and switch errors. Multiple visualizations, such as k-mer spectrum plots, can be generated for evaluation. We demonstrate on both human and plant genomes that Merqury is a fast and robust method for assembly validation.Availability of data and materialProject name: MerquryProject home page: https://github.com/marbl/merqury, https://github.com/marbl/merylArchived version: https://github.com/marbl/merqury/releases/tag/v1.0Operating system(s): Platform independentProgramming language: C++, Java, PerlOther requirements: gcc 4.8 or higher, java 1.6 or higherLicense: Public domain (see https://github.com/marbl/merqury/blob/master/README.license) Any restrictions to use by non-academics: No restrictions applied

scholarly journals Phased diploid genome assemblies for three strains of Candida albicans from oak trees

2019 ◽  
Author(s):  
Jennafer A. P. Hamlin ◽  
Guilherme Dias ◽  
Casey M. Bergman ◽  
Douda Bensasson
Keyword(s):  
Candida Albicans ◽  
De Novo ◽  
Bloodstream Infections ◽  
Genomic Variation ◽  
High Rate ◽  
The United Kingdom ◽  
Oak Trees ◽  
Wide Range ◽  
Animal Hosts ◽  
Genome Assemblies

ABSTRACTAlthough normally a harmless commensal, Candida albicans has the potential to generate a wide range of infections including systemic candidaemia, making it the most common cause of bloodstream infections worldwide with a high rate of mortality. C. albicans has long been considered an obligate commensal, however, recent studies suggest it can live outside animal hosts. Here, we have generated PacBio sequencing and phased genome assemblies for three C. albicans strains from oak trees in the United Kingdom (NCYC 4144, NCYC 4145, and NCYC 4146). Our results provide phased de novo diploid assemblies for C. albicans and provide a framework to study patterns of genomic variation within and among strains of an important fungal pathogen.

scholarly journals Massive rhizobial genomic variation associated with partner quality in Lotus–Mesorhizobium symbiosis

2020 ◽  
Vol 96 (12) ◽  
Author(s):  
Masaru Bamba ◽  
Seishiro Aoki ◽  
Tadashi Kajita ◽  
Hiroaki Setoguchi ◽  
Yasuyuki Watano ◽  
...  
Keyword(s):  
Core Genome ◽  
De Novo ◽  
Lotus Japonicus ◽  
Genomic Variation ◽  
The Novel ◽  
High Quality ◽  
Cooperative Relationships ◽  
The Core ◽  
Quality Variation

ABSTRACT Variation in partner quality is commonly observed in diverse cooperative relationships, despite the theoretical prediction that selection favoring high-quality partners should eliminate such variation. Here, we investigated how genetic variation in partner quality could be maintained in the nitrogen-fixing mutualism between Lotus japonicus and Mesorhizobium bacteria. We reconstructed de novo assembled full-genome sequences from nine rhizobial symbionts, finding massive variation in the core genome and the similar symbiotic islands, indicating recent horizontal gene transfer (HGT) of the symbiosis islands into diverse Mesorhizobium lineages. A cross-inoculation experiment using 9 sequenced rhizobial symbionts and 15 L. japonicus accessions revealed extensive quality variation represented by plant growth phenotypes, including genotype-by-genotype interactions. Variation in quality was not associated with the presence/absence variation in known symbiosis-related genes in the symbiosis island; rather, it showed significant correlation with the core genome variation. Given the recurrent HGT of the symbiosis islands into diverse Mesorhizobium strains, local Mesorhizobium communities could serve as a major source of variation for core genomes, which might prevent variation in partner quality from fixing, even in the presence of selection favoring high-quality partners. These findings highlight the novel role of HGT of symbiosis islands in maintaining partner quality variation in the legume–rhizobia symbiosis.

scholarly journals Genomic analyses provide insights into spinach domestication and the genetic basis of agronomic traits

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaofeng Cai ◽  
Xuepeng Sun ◽  
Chenxi Xu ◽  
Honghe Sun ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Agronomic Traits ◽  
Association Studies ◽  
Genome Wide Association Studies ◽  
Repeat Content ◽  
Genome Wide ◽  
Leaf Phenotype ◽  
The Family ◽  
Genomic Analyses ◽  
Agronomical Traits

AbstractSpinach is a nutritious leafy vegetable belonging to the family Chenopodiaceae. Here we report a high-quality chromosome-scale reference genome assembly of spinach and genome resequencing of 305 cultivated and wild spinach accessions. Reconstruction of ancestral Chenopodiaceae karyotype indicates substantial genome rearrangements in spinach after its divergence from ancestral Chenopodiaceae, coinciding with high repeat content in the spinach genome. Population genomic analyses provide insights into spinach genetic diversity and population differentiation. Genome-wide association studies of 20 agronomical traits identify numerous significantly associated regions and candidate genes for these traits. Domestication sweeps in the spinach genome are identified, some of which are associated with important traits (e.g., leaf phenotype, bolting and flowering), demonstrating the role of artificial selection in shaping spinach phenotypic evolution. This study provides not only insights into the spinach evolution and domestication but also valuable resources for facilitating spinach breeding.

scholarly journals Pan-genome Analysis in Sorghum Highlights the Extent of Genomic Variation and Sugarcane Aphid Resistance Genes

2021 ◽  
Author(s):  
Bo Wang ◽  
Yinping Jiao ◽  
Kapeel Chougule ◽  
Andrew Olson ◽  
Jian Huang ◽  
...  
Keyword(s):  
De Novo ◽  
Genomic Variation ◽  
R Genes ◽  
Structural Variations ◽  
Transcription Start Sites ◽  
Pan Genome ◽  
Sugarcane Aphid ◽  
Genome Wide ◽  
Genome Assemblies ◽  
High Degree

ABSTRACTSorghum bicolor, one of the most important grass crops around the world, harbors a high degree of genetic diversity. We constructed chromosome-level genome assemblies for two important sorghum inbred lines, Tx2783 and RTx436. The final high-quality reference assemblies consist of 19 and 18 scaffolds, respectively, with contig N50 values of 25.6 and 20.3 Mb. Genes were annotated using evidence-based and de novo gene predictors, and RAMPAGE data demonstrate that transcription start sites were effectively captured. Together with other public sorghum genomes, BTx623, RTx430, and Rio, extensive structural variations (SVs) of various sizes were characterized using Tx2783 as a reference. Genome-wide scanning for disease resistance (R) genes revealed high levels of diversity among these five sorghum accessions. To characterize sugarcane aphid (SCA) resistance in Tx2783, we mapped the resistance region on chromosome 6 using a recombinant inbred line (RIL) population and found a SV of 191 kb containing a cluster of R genes in Tx2783. Using Tx2783 as a backbone, along with the SVs, we constructed a pan-genome to support alignment of resequencing data from 62 sorghum accessions, and then identified core and dispensable genes using this population. This study provides the first overview of the extent of genomic structural variations and R genes in the sorghum population, and reveals potential targets for breeding of SCA resistance.

scholarly journals Reference genome and resequencing of 305 accessions provide insights into spinach evolution, domestication and genetic basis of agronomic traits

2021 ◽  
Author(s):  
Xiaofeng Cai ◽  
Xuepeng Sun ◽  
Chenxi Xu ◽  
Honghe Sun ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Reference Genome ◽  
Agronomic Traits ◽  
Association Studies ◽  
Genome Wide Association Studies ◽  
Total Size ◽  
Repeat Content ◽  
Genome Wide ◽  
Leaf Phenotype ◽  
Agronomical Traits

Spinach is a nutritious leafy vegetable belonging to the family Chenopodiaceae. Here we report a chromosome-scale reference genome assembly of spinach, which has a total size of 894.3 Mb and an N50 contig size of 23.8 Mb, with 98.3% anchored and ordered on the six chromosomes. Reconstruction of ancestral Chenopodiaceae karyotype indicates substantial genome rearrangements in spinach after its divergence from ancestral Chenopodiaceae, coinciding with high repeat content in the spinach genome. Resequencing the genomes of 305 cultivated and wild spinach accessions provides insights into spinach genetic diversity and population differentiation. Genome-wide association studies of 20 agronomical traits identify numerous significantly associated regions and candidate genes for these traits. Domestication sweeps in the spinach genome are identified, some of which are associated with important traits (e.g., leaf phenotype, bolting and flowering), demonstrating the role of artificial selection in shaping spinach phenotypic evolution. This study provides not only insights into the spinach evolution and domestication but also valuable resources for facilitating spinach breeding.

scholarly journals Merqury: reference-free quality, completeness, and phasing assessment for genome assemblies

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Arang Rhie ◽  
Brian P. Walenz ◽  
Sergey Koren ◽  
Adam M. Phillippy
Keyword(s):  
De Novo ◽  
High Accuracy ◽  
Robust Method ◽  
Plant Genomes ◽  
Base Level ◽  
Set Operations ◽  
Assembly Evaluation ◽  
Long Read ◽  
Genome Assemblies ◽  
Reference Genomes

Abstract Recent long-read assemblies often exceed the quality and completeness of available reference genomes, making validation challenging. Here we present Merqury, a novel tool for reference-free assembly evaluation based on efficient k-mer set operations. By comparing k-mers in a de novo assembly to those found in unassembled high-accuracy reads, Merqury estimates base-level accuracy and completeness. For trios, Merqury can also evaluate haplotype-specific accuracy, completeness, phase block continuity, and switch errors. Multiple visualizations, such as k-mer spectrum plots, can be generated for evaluation. We demonstrate on both human and plant genomes that Merqury is a fast and robust method for assembly validation.

Ionic homeostasis and subcellular element compartmentation

1990 ◽  
Vol 48 (2) ◽  
pp. 150-151
Author(s):  
Ann LeFurgey ◽  
Peter Ingram ◽  
J.J. Blum ◽  
M.C. Carney ◽  
L.A. Hawkey ◽  
...  
Keyword(s):  
Leishmania Major ◽  
Ionic Homeostasis ◽  
X Ray ◽  
Functional Studies ◽  
Cell Compartments ◽  
X Ray Imaging ◽  
Resolution Electron ◽  
Multiple Cell ◽  
Role Of Zn

Subcellular compartments commonly identified and analyzed by high resolution electron probe x-ray microanalysis (EPXMA) include mitochondria, cytoplasm and endoplasmic or sarcoplasmic reticulum. These organelles and cell regions are of primary importance in regulation of cell ionic homeostasis. Correlative structural-functional studies, based on the static probe method of EPXMA combined with biochemical and electrophysiological techniques, have focused on the role of these organelles, for example, in maintaining cell calcium homeostasis or in control of excitation-contraction coupling. New methods of real time quantitative x-ray imaging permit simultaneous examination of multiple cell compartments, especially those areas for which both membrane transport properties and element content are less well defined, e.g. nuclei including euchromatin and heterochromatin, lysosomes, mucous granules, storage vacuoles, microvilli. Investigations currently in progress have examined the role of Zn-containing polyphosphate vacuoles in the metabolism of Leishmania major, the distribution of Na, K, S and other elements during anoxia in kidney cell nuclel and lysosomes; the content and distribution of S and Ca in mucous granules of cystic fibrosis (CF) nasal epithelia; the uptake of cationic probes by mltochondria in cultured heart ceils; and the junctional sarcoplasmic retlculum (JSR) in frog skeletal muscle.

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