GBS-based identification of Triticum timopheevii introgressions in a wheat pre-breeding population
A wheat × T. timopheevii pre-breeding population was analyzed using Genotyping-by-sequencing (GBS) combined with a skim-seq pipeline to identify and characterize T. timopheevii introgressions. Read coverage analysis based on a combined T. aestivum–T. timopheevii reference genome enabled high-resolution detection of major chromosomal introgressions and copy-number changes. Sequencing reads were aligned to this combined assembly, and chromosome identity and physical position could be extracted. An \"in silico wheat × T. timopheevii hybrid\" reference genome was constructed by combining the reference sequences of the donor and the recipient species. To identify wheat-T. timopheevii introgressions, we combined the Chinese Spring reference genome (IWGSC RefSeq v1.0) (IWGSC, 2018) with the draft genome assembly of T. timopheevii (GCA_963921465.1) (Grewal et al., 2024). During the assembly process, unique identifiers were assigned to all chromosomes or pseudomolecules to maintain distinctiveness.  Prior to alignment, the Illumina short reads from 42 lines, along with the previously described control genotypes, were demultiplexed and adapter-trimmed with Stacks v2.68 (Rochette et al., 2019). The processed paired-end reads were then mapped separately to the combined reference genome using HISAT v2.1.0 (Kim et el., 2019) with the – no-spliced-alignment and – no-unal parameters. Following alignment, concordant unique reads were retrieved by filtering the sequence alignment map (SAM) outputs for the YT:Z:CP and NH:i:1 tags.
A wheat × T. timopheevii pre-breeding population was analyzed using Genotyping-by-sequencing (GBS) combined with a skim-seq pipeline to identify and characterize T. timopheevii introgressions. Read coverage analysis based on a combined T. aestivum–T. timopheevii reference genome enabled high-resolution detection of major chromosomal introgressions and copy-number changes. Sequencing reads were aligned to this combined assembly, and chromosome identity and physical position could be extracted. An \"in silico wheat × T. timopheevii hybrid\" reference genome was constructed by combining the reference sequences of the donor and the recipient species. To identify wheat-T. timopheevii introgressions, we combined the Chinese Spring reference genome (IWGSC RefSeq v1.0) (IWGSC, 2018) with the draft genome assembly of T. timopheevii (GCA_963921465.1) (Grewal et al., 2024). During the assembly process, unique identifiers were assigned to all chromosomes or pseudomolecules to maintain distinctiveness.  Prior to alignment, the Illumina short reads from 42 lines, along with the previously described control genotypes, were demultiplexed and adapter-trimmed with Stacks v2.68 (Rochette et al., 2019). The processed paired-end reads were then mapped separately to the combined reference genome using HISAT v2.1.0 (Kim et el., 2019) with the – no-spliced-alignment and – no-unal parameters. Following alignment, concordant unique reads were retrieved by filtering the sequence alignment map (SAM) outputs for the YT:Z:CP and NH:i:1 tags.
European Bioinformatics Institute