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How to handle hexaploidy of Wheat for vcf file

I have a GBS data for wheat. I mapped it to reference and then used freebayes for variant calling. it has the option for ploidy. so should I used 6 or 2 ? bcoz as wheat is hexploid but the reference has chromosomes sequences as 1A, 1B and 1C. so keeping in mind I should be using the parameter ploidy with 2. Am I doing it right ? if someone could enlighten me ?

gbs next-gen vcf

One way (only my guess) would be to look at genotypes/info available in ensembl plants website for wheat ( https://plants.ensembl.org/Triticum_aestivum/Info/Index a quote from the website "Bread wheat is hexaploid, with a genome size estimated at ~17 Gb, composed of three closely-related and independently maintained genomes " ) . Also looking at genotypes of SNPs in ensembl plants which seem to be standard diploid (https://plants.ensembl.org/Triticum_aestivum/Variation/Population?db=core;g=TraesCS3D02G273600;r=3D:379535906-379539827;t=TraesCS3D02G273600.1;v=BA00408873;vdb=variation;vf=224541 ). Overall my hunch would be that since the subgenomes are present in the reference fasta diploid genotypes would make sense.

This is not relevant for your work. But Tassel pipeline is designed for handling wheat GBS data.

ok..!! May be I m wrong but Tassel is mainly designed for maize which is diploid.

1 answer

Yes, you need to set your ploidy value to 6, this can produce VCFs with more complex representation of variants

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