Marker Effects for Fusarium Head Blight Resistance and the Dwarfing Gene <i>Rht‐B1</i> in Cultivated Emmer Wheat (<scp><i>Triticum turgidum</i></scp> ssp. <i>dicoccum</i>) Revealed by Association Mapping

ABSTRACT Fusarium head blight (FHB) is a disease that affects all cereals worldwide. This includes emmer wheat ( Triticum turgidum ssp. dicoccum ), the ancestor of durum and bread wheat. We screened 143 cultivated emmer genotypes from a breeding program and gene bank collections for FHB severity at 2 locations over 2 years. Due to the high negative correlation between FHB severity and heading date (HD) ( r = −0.65, p &lt; 0.001), plot‐level FHB scores were corrected for HD before further analysis (FHB corr ). Genetic variation for FHB severity was high, ranging from 2.15 to 8.33 on a 1–9 scale. Twelve genotypes carried the semi‐dwarfing Rht‐B1b marker allele, which reduced plant height by 32 cm but increased FHB severity by 20%. Genome‐wide association study detected seven quantitative trait nucleotides (QTNs) for FHB corr and three QTNs for plant height. The most important QTN for both traits was located on chromosome 4B, explaining 50.9% and 15.8% of the phenotypic variation in plant height and FHB corr , respectively, and was localized near the semi‐dwarfing Rht‐B1 locus. Three other large‐effect loci for FHB corr were found on chromosomes 5B and 7B. In total, 72.6% of phenotypic variation was explained by all markers. The use of Rht‐B1b in emmer breeding has a high effect on plant height but would entail the introgression of potent FHB‐resistance from either native or exotic sources.