A large nested association mapping population for breeding and quantitative trait locus mapping in Ethiopian durum wheat

Summary The Ethiopian plateau hosts thousands of durum wheat ( Triticum turgidum subsp. durum ) farmer varieties ( FV ) with high adaptability and breeding potential. To harness their unique allelic diversity, we produced a large nested association mapping ( NAM ) population intercrossing fifty Ethiopian FV s with an international elite durum wheat variety (Asassa). The Ethiopian NAM population (Et NAM ) is composed of fifty interconnected bi‐parental families, totalling 6280 recombinant inbred lines ( RIL s) that represent both a powerful quantitative trait loci ( QTL ) mapping tool, and a large pre‐breeding panel. Here, we discuss the molecular and phenotypic diversity of the Et NAM founder lines, then we use an array featuring 13 000 single nucleotide polymorphisms ( SNP s) to characterize a subset of 1200 Et NAM RIL s from 12 families. Finally, we test the usefulness of the population by mapping phenology traits and plant height using a genome wide association ( GWA ) approach. Et NAM RIL s showed high allelic variation and a genetic makeup combining genetic diversity from Ethiopian FV s with the international durum wheat allele pool. Et NAM SNP data were projected on the fully sequenced AB genome of wild emmer wheat, and were used to estimate pairwise linkage disequilibrium ( LD ) measures that reported an LD decay distance of 7.4 Mb on average, and balanced founder contributions across Et NAM families. GWA analyses identified 11 genomic loci individually affecting up to 3 days in flowering time and more than 1.6 cm in height. We argue that the Et NAM is a powerful tool to support the production of new durum wheat varieties targeting local and global agriculture.