Introgression of barley chromosome arms 4H and 6H into wheat via Robertsonian translocations: GBS-assisted structural analysis and impact on grain nutrient composition

In addition to wild relatives, cultivated Triticeae species such as barley can also serve as an excellent gene source to improve the agronomic traits of bread wheat. The Asakaze-Manas addition lines previously developed in Martonvásár exhibit low fertility and unstable inheritance; nonetheless, they could serve as ’bridge materials’ for the incorporation of barley chromatin into the wheat genome. By leveraging the centric breakage-fusion mechanism of unpaired chromosomes and the gametocidal effect of chromosome 2C from Aegilops cylindrica, the 4H and 6H addition lines were used to develop genetically stable translocation genotypes. In situ hybridization and molecular marker analyses were applied to identify the wheat and barley chromosome arms in the compensatory translocations, designated as T6HS.6BL, T6BS.6HL and T4BS.4HL. These results were confirmed by GBS read coverage analysis, which revealed a putative pericentric inversion in the barley chromosome arms involved in the T6HS.6BL and T6BS.6HL. The comparable agronomic performance of the centric fusion lines indicates that these chromosomal rearrangements had minimal, if any, negative impact relative to the parental wheat varieties. The newly developed translocation lines had an increased amount of minerals such as iron, suggesting that they could serve as promising genetic material for the biofortification of hexaploid wheat. Molecular marker analysis and in situ hybridization techniques, combined with genotyping-by-sequencing, enable the selection of stable wheat-barley translocation lines, leading to chromosome-mediated improvement in grain quality.