DArTseq genotyping facilitates identification of Aegilops biuncialis chromatin introgressed into bread wheat Mv9kr1

Abstract Aegilops species, wild relatives of wheat, offer valuable traits for wheat improvement through interspecific hybridization. Despite many Ae. biuncialis accessions maintained in gene banks, only a few have been utilized in wheat breeding. Gene transfer from Aegilops has been hampered by difficulties in detecting introgressed Ub- and Mb-genome chromatin at high resolution in the wheat background. The present study applied DArTseq technology, to genotype two backcrossed populations (BC382, BC642) derived from crosses of a wheat line Mv9kr1 with Ae. biuncialis accession, MvGB382 (earlyflowering and drought tolerant) and MvGB642 (leaf rust-resistant). 11,952 Aegilops specific Silico-DArT markers were obtained, while 8998 markers were specific to wheat. Using the results obtained on diploid progenitors and wheat-Aegilops addition lines, 7686 markers were assigned to the Ub-genome chromosomes and 4266 for Mb-genome chromosomes and ordered by the use of chromosome assemblies of hexaploid wheat and Ae. umbellulata. In the BC3 populations, 5.7% of BC382 and 22.7% of BC642 lines contained Ub-genome chromatin, while Mb-genome chromatin was detected in 88.5% of BC382 and 84% of BC642 lines. Notably, chromosomes 4Mb and 5Mb were frequently present in both populations, whereas chromosomes 3Mb and 6Mb were rarer. A Mv9kr1-Ae. biuncialis MvGB382 4Mb and 5Mb disomic addition lines were identified together with a new 5DS.5DL-5MbL recombination. Moreover, previously developed Mv9kr1-MvGB642 introgression lines were identified more precisely by DArTseq. A possible effect of the 5MbL distal region on seed length has been also observed and discussed. The new cytogenetic stocks represent valuable genetic resources for wheat improvement.