Introgression of Aegilops speltoides segments in Triticum aestivum and the effect of the gametocidal genes

BACKGROUND AND AIMS: Bread wheat (Triticum aestivum) has been through a severe genetic bottleneck as a result of its evolution and domestication. It is therefore essential that new sources of genetic variation are generated and utilized. This study aimed to generate genome-wide introgressed segments from Aegilops speltoides. Introgressions generated from this research will be made available for phenotypic analysis. METHODS: Aegilops speltoides was crossed as the male parent to T. aestivum ‘Paragon’. The interspecific hybrids were then backcrossed to Paragon. Introgressions were detected and characterized using the Affymetrix Axiom Array and genomic in situ hybridization (GISH). KEY RESULTS: Recombination in the gametes of the F(1) hybrids was at a level where it was possible to generate a genetic linkage map of Ae. speltoides. This was used to identify 294 wheat/Ae. speltoides introgressions. Introgressions from all seven linkage groups of Ae. speltoides were found, including both large and small segments. Comparative analysis showed that overall macro-synteny is conserved between Ae. speltoides and T. aestivum, but that Ae. speltoides does not contain the 4A/5A/7B translocations present in wheat. Aegilops speltoides has been reported to carry gametocidal genes, i.e. genes that ensure their transmission through the gametes to the next generation. Transmission rates of the seven Ae. speltoides linkage groups introgressed into wheat varied. A 100 % transmission rate of linkage group 2 demonstrates the presence of the gametocidal genes on this chromosome. CONCLUSIONS: A high level of recombination occurs between the chromosomes of wheat and Ae. speltoides, leading to the generation of large numbers of introgressions with the potential for exploitation in breeding programmes. Due to the gametocidal genes, all germplasm developed will always contain a segment from Ae. speltoides linkage group 2S, in addition to an introgression from any other linkage group.