Characterization of Fusarium head blight resistance in a CIMMYT synthetic-derived bread wheat line

Fusarium head blight (FHB), also known as head scab, is a devastating fungal disease of bread and durum wheat worldwide. It reduces yield, lowers seed germination, reduces grain quality, and renders grain unsuitable for human or animal consumption due to mycotoxin contamination. Use of host resistance in commercially cultivated wheat varieties is an economical, effective and environmentally friendly method to manage FHB. In order to map loci underlying FHB resistance in synthetic-derived bread wheat line SYN1, a doubled haploid (DH) population of 169 lines was developed through hybridizing SYN1 with FHB-susceptible line Ocoroni. The DH population was evaluated in spray-inoculated field nurseries in the 2010 and 2011 cropping seasons at the El Batan Experiment Station of the International Maize and Wheat Improvement Center, Mexico. Ten marked spikes from each plot were scored for disease response and an FHB index was subsequently calculated. The population was genotyped with 1391 genotyping by sequencing and 106 simple-sequence repeat (SSR) loci and 28 linkage groups were constructed. These linkage groups were anchored by SSRs to all chromosomes, except 4D, 5D and 6D. Using the inclusive composite interval mapping algorithm, three genomic regions were associated with FHB resistance, including a major QTL on chromosome 2D accounting for 25 % of the phenotypic variation explained (PVE) and two minor QTLs on chromosomes 1B (4.7 % PVE) and 7A (4.2 % PVE), with all favorable alleles contributed by SYN1. The average FHB index of lines with all three SYN1 alleles was substantially lower (61.4 %) than that of those with Ocoroni alleles.