The transfer of 98% of the genome of Aegilops mutica into wheat (Triticum aestivum)

KEY MESSAGE: New wheat-Ae. mutica introgression lines will deliver new genetic variation for hexaploid wheat breeding and provide new information on the distribution of homoeologous recombination between wheat and Ae. mutica. Aegilops mutica Boiss. (2n = 2 × = 14, TT) is a wild relative of wheat that has been underutilised as a source of genetic variation for hexaploid wheat Triticum aestivum L. (2n = 6 × = 42; AABBDD), despite its potential to harbour important genetic diversity for a wide range of agronomically valuable traits. This species has been extensively exploited by the Wheat Research Centre (WRC) at the University of Nottingham to create a diverse resource of wheat-Ae. mutica introgression lines. In this study, we present the most comprehensive transfer of the Ae. mutica genome into wheat to date, with 98% of the genome now present in wheat through the development of new wheat-Ae. mutica introgression lines. These 68 new lines, comprising 57 unique Ae. mutica introgressions, have been characterised using kompetitive allele-specific PCR (KASP) genotyping, multi-colour genomic in situ hybridisation and low coverage whole-genome sequencing. This thorough characterisation has revealed the distribution of homoeologous recombination sites between wheat and Ae. mutica chromosomes, uncovering recombination "hotspots" and novel introgressed segments that were previously undetectable using conventional genotyping methods. This resource significantly expands the genetic diversity available for wheat improvement and offers a powerful platform for linking traits to specific genotypes. The creation and characterisation of this near-complete set of Ae. mutica introgressions will be invaluable for wheat researchers and breeders worldwide.