Mapping Yield and Yield-Component QTL in a Durum Wheat (Triticum turgidum ssp. durum) Multi-Parental Cross Population

Multiparental cross designs for mapping quantitative trait loci (QTLs) in crops are efficient alternatives to conventional biparental crosses because they exploit a broader genetic basis and are characterized by higher mapping resolution. We assembled a recombinant inbred population (338 F_7:8 RILs) in durum wheat (Triticum durum Desf.) from a balanced four-way cross of four elite cultivars (Neodur, Claudio, Colosseo and Rascon/Tarro. NCCR). NCCR was phenotyped in four-environment field trials for 18 traits, including yield, yield-components, morpho-physiological and quality traits. A linkage map spanning 2,663 cM and including 7,594 single nucleotide polymorphisms (SNPs) was produced by genotyping 338 RILs with a wheat-dedicated 90K SNP array. QTL analysis enabled us to detect 62 QTLs. Two QTLs for grain yield were mapped across environments and 23 QTLs for grain yield components. A novel major QTL for number of grain per spikelet/ear was mapped on chr 2A and shown to control up to 39% of phenotypic variance. Despite the four founders, an average of only 2.1 different functional haplotypes were estimated per QTL. More generally, our QTL results confirmed the importance of relatively minor and environment-specific QTL in controlling grain yield in the elite durum wheat germplasm.