Genetic architecture of yellow and stem rust resistance in a durum wheat diversity panel

Winter durum (Triticum turgidum var. durum) growing is favored in Germany, Austria, and Hungary. With the invasion of the aggressive Warrior race with a wider virulence spectrum of the yellow rust (YR) causing pathogen, YR came into focus of durum breeders. Accordingly, a local epidemic of stem rust in winter wheat 2013 gained much attention. Therefore, we aimed to analyze the genetic architecture of resistance to YR and stem rust (SR) in a diversity panel of 328 durum lines genotyped by 12,550 mapped markers. Infections were successful in three environments for YR and one environment for SR. Additionally, cumulative ratings of leaf and ear health were conducted in five and three environments, respectively. The genome-wide association analysis revealed six to eight quantitative trait loci (QTL) per trait with an explained total genotypic variance of 42% (YR) to 75% (ear health). Sequence comparison with a reference genome indicated that three YR (Yr10, Yr51, YrH9014) and two SR (Sr56, Sr8155B1) resistance genes might be present in the diversity panel. Other QTL with explained genotypic variances ranging from 1.5 to 21% were detected. The difference between marker-assisted selection and genomic prediction was the highest for those traits with lower explained genetic variance (YR, leaf health) indicating that an array of non-detected QTL was used for genomic prediction. Genomics-assisted breeding could greatly help in achieving complex resistances in cultivars.