Recombination and structural variation in a large 8-founder wheat MAGIC population.

Identifying the genetic architecture of complex traits requires access to populations with sufficient genetic diversity and recombination. Multiparent Advanced Generation InterCross (MAGIC) populations are a powerful resource due to their balanced population structure, allelic diversity, and enhanced recombination. However, implementing a MAGIC population in complex polyploids such as wheat is challenging, as wheat harbors many introgressions, inversions, and other genetic factors that interfere with linkage mapping. By utilizing a comprehensive crossing strategy, additional rounds of mixing, and novel genotype calling approaches, we developed a bread wheat 8-parent MAGIC population of over 3,000 genotyped recombinant inbred lines derived from 2,151 distinct crosses. This effort resulted in a dense genetic map covering the complete genome. Further rounds of intercrossing led to increased recombination in inbred lines, as expected. We identified structural variation highlighted by segregation distortion, along with epistatic allelic interactions between specific founders. We report on a novel and effective resource for genomic and trait exploration in hexaploid wheat, capable of detecting small genetic effects and epistatic interactions due to the high level of recombination and large number of lines. The interactions and genetic effects identified provide a basis for ongoing research to understand the basis of allelic frequencies across the genome, particularly where economically important loci are involved.