Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Distribution, functional impact and origin mechanisms of copy number variation in the barley genome

ABSTRACT: There is growing evidence for the prevalence of DNA copy number variation (CNV) and its role in phenotypic variation in recent years. Comparative genomic hybridization (CGH) was used to explore the extent of this type of structural variation in the barley genome. In a panel of 14 genotypes including domesticated cultivars and wild barleys, we found that 14.9% of all the sequences on the array are affected by CNV. Higher levels of CNV diversity are present in the wild accessions relative to cultivated barley. A substantial portion (37%) of the CNV events are present in both wild and domesticated barley. CNVs are enriched in telomeric regions for all chromosomes except 4H, which is also the barley chromosome with the lowest proportion of CNVs. CNV affected 9.5% of the coding sequences represented on the array. The genes affected by CNV are enriched for sequences annotated as disease-resistance proteins and protein kinases, suggesting the potential for CNV to influence variation for responses to biotic and abiotic stress. The analysis of CNV breakpoints indicated that DNA repair mechanisms of double-strand breaks (DSBs) via single-stranded annealing (SSA) and synthesis-dependent strand annealing (SDSA) play an important role in the origin of many structural changes in barley. Here we present the first catalog of CNVs in a diploid Triticeae species, which opens the door for future genome diversity research in a tribe that comprises the economically important cereal species wheat, barley and rye. Our findings constitute a valuable resource for the identification of CNV affecting genes of agronomic importance. 1-2 replications of 8 barley cultivars and 6 wild barley accessions were hybridized to an array designed from 115,003 whole genome shotgun (WGS) contigs of the ‘reference’ genome of cv. Morex

ORGANISM(S): Hordeum vulgare subsp. vulgare

SUBMITTER: María Muñoz-Amatriaín

PROVIDER: E-GEOD-44293 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Genomic structural variation is an important and abundant source of genetic and phenotypic variation. Here we describe the first systematic and genome-wide analysis of copy number variations (CNVs) in modern domesticated cattle using array comparative genomic hybridization (array CGH), quantitative PCR (qPCR) and fluorescent in situ hybridization (FISH). The array CGH panel included 90 animals from 11 Bos taurus, 3 Bos indicus and 3 composite breeds for beef, dairy or dual purpose. We identified over 200 candidate CNV regions (CNVRs) in total and 177 within known chromosomes, which harbor or are adjacent to gains or losses. These 177 high-confidence CNVRs cover 28.1 mega bases or ~1.07% of the genome. Over 50% of the CNVRs (89/177) were found in multiple animals or breeds and analysis revealed breed-specific frequency differences and reflected aspects of the known ancestry of these cattle breeds. Selected CNVs were further validated by independent methods using qPCR and FISH. Approximately 67% of the CNVRs (119/177) completely or partially span cattle genes and 61% of the CNVRs (108/177) directly overlap with segmental duplications. The CNVRs span about 400 annotated cattle genes that are significantly enriched for specific biological functions such as immunity, lactation, reproduction and rumination. Multiple gene families, including ULBP, have gone through ruminant lineage-specific gene amplification. We detected and confirmed marked differences in their CNV frequencies across diverse breeds, indicating that some cattle CNVs are likely to arise independently in breeds and contribute to breed differences. Our results provide a valuable resource beyond microsatellites and single nucleotide polymorphisms to explore the full dimension of genetic variability for future cattle genomic research. The custom aCGH chips that interrogated the whole genome CNVs were build for 90 cattles from diverse breeds, with Hereford L1 Dominette 01449 as refference sample.

Project description:Different individuals of the same species are generally thought to have very similar genomes. However, there is growing evidence that structural variation in the form of copy number variation (CNV) and presence-absence variation (PAV) can lead to variation in the genome content of individuals within a species. In order to investigate the potential contribution of CNV and PAV to genomic diversity in maize we used array comparative genomic hybridization (CGH) to compare gene content and copy number variation among 25 diverse maize inbreds 14 genotypes of the wild ancestor of maize, teosinte. The microarray included multiple probes for each of the ~32,500 stringently filtered genes identified in the B73 reference genome. We identified 479 genes exhibiting higher copy number in some genotypes (UpCNV) and 3,410 genes that have either fewer copies or are missing in the genome of at least one genotype relative to B73 (DownCNV/PAV). Many of these DownCNV/PAV are examples of genes that are present in B73 but missing from the genome of several other genotypes. Over 70% of the CNV/PAV examples are identified in multiple genotypes and the majority of events are observed in both maize and teosinte suggesting that these reflect relatively old variants that are not associated with domestication or maize improvement. Many of the genes affected by CNV/PAV are either maize-specific or members of genes families suggesting that the gene loss can be tolerated through buffering by redundant functions encoded elsewhere in the genome. Many plant genomes are relatively large and contain the remnant of whole genome duplications which may provide the ability to tolerate high levels of structural variation. While this structural variation may not result in major qualitative variation due to genetic buffering, it may significantly contribute to quantitative variation. 1-2 replications of 25 maize inbred and 14 teosinte genotypes were hybridized to an array designed from the ~32,400 genes in the maize B73 reference genome.

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Distribution, functional impact and origin mechanisms of copy number variation in the barley genome

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