Comparative transcriptomics in the Triticeae

<p>Abstract</p> <p>Background</p> <p>Barley and particularly wheat are two grass species of immense agricultural importance. In spite of polyploidization events within the latter, studies have shown that genotypically and phenotypically these species are very closely related and, indeed, fertile hybrids can be created by interbreeding. The advent of two genome-scale Affymetrix GeneChips now allows studies of the comparison of their transcriptomes.</p> <p>Results</p> <p>We have used the Wheat GeneChip to create a "gene expression atlas" for the wheat transcriptome (cv. Chinese Spring). For this, we chose mRNA from a range of tissues and developmental stages closely mirroring a comparable study carried out for barley (cv. Morex) using the Barley1 GeneChip. This, together with large-scale clustering of the probesets from the two GeneChips into "homologous groups", has allowed us to perform a genomic-scale comparative study of expression patterns in these two species. We explore the influence of the polyploidy of wheat on the results obtained with the Wheat GeneChip and quantify the correlation between conservation in gene sequence and gene expression in wheat and barley. In addition, we show how the conservation of expression patterns can be used to elucidate, probeset by probeset, the reliability of the Wheat GeneChip.</p> <p>Conclusion</p> <p>While there are many differences in expression on the level of individual genes and tissues, we demonstrate that the wheat and barley transcriptomes appear highly correlated. This finding is significant not only because given small evolutionary distance between the two species it is widely expected, but also because it demonstrates that it is possible to use the two GeneChips for comparative studies. This is the case even though their probeset composition reflects rather different design principles as well as, of course, the present incomplete knowledge of the gene content of the two species. We also show that, in general, the Wheat GeneChip is not able to distinguish contributions from individual homoeologs. Furthermore, the comparison between the two species leads us to conclude that the conservation of both gene sequence as well as gene expression is positively correlated with absolute expression levels, presumably reflecting increased selection pressure on genes coding for proteins present at high levels. In addition, the results indicate the presence of a correlation between sequence and expression conservation within the Triticeae.</p

Wyalkatchem WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Wyalkatchem (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

Alsen WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Alsen (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

Pastor WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Pastor (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

Excalibur WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Excalibur (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

Baxter WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Baxter (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

Drysdale WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Drysdale (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

Chara,AUS WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of Chara,AUS (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part

RAC-875 WGS vs IWGSC RefSeq v1.0 Genome Assembly

WGS reads of RAC-875 (http://dx.doi.org/10.1111/j.1467-7652.2012.00717.x) were aligned against the IWGSC <i>Triticum aestivum</i> Chinese Spring RefSeq v1.0 genome assembly using Minimap2. These BAM files (.bam) and index files (.bam.bai) are provided together with a summary of read alignment coverage bigWig files (.bam.bw). SNP variants were called from these BAM files to generate VCF files (.bam.vcf.gz) and index files (.bam.vcf.gz.tbi) and are provided together with a summary of SNP density (SNPs per 10 kbp) bigWig files (.bam.vcf.w10000_s10000.bw). VCF files contain the following filter values and corresponding meaning: PASS = high quality (Q>=30) homozygous; Het = high quality (Q>=30) heterozygous; LowQualHom = low quality (Q<30) homozygous; LowQualHet = low quality (Q<30) heterozygous. Files are provided separately for each chromosome part