Comparison of phenotypic and marker-based selection for Fusarium head blight resistance and DON content in spring wheat

Fusarium head blight (FHB) is one of the most economically important wheat diseases, resulting in losses in grain yield and quality as well as contamination with deoxynivalenol (DON). Cultivar Sumai 3 from China and its descendants as well as var. Frontana from Brazil have been identified as potent sources of resistance and subsequently mapped by molecular markers. The aim of the present study was to compare phenotypic and marker-based selection in spring wheat. In a double cross, we combined two donor-quantitative trat loci (QTL) alleles from CM82036 (Sumai 3/Thornbird) located on chromosomes 3B and 5A and one donor-QTL allele from var. Frontana on chromosome 3A with two high-yielding German spring wheat varieties. This initial population was selected phenotypically by a two- (CP1) and three-step procedure (CP1⁺) and by independent marker-based analysis using one to three flanking markers per QTL (CM). To estimate selection gain, the two phenotypically selected variants and the marker-selected variant as well as an unselected variant (C0) were inoculated with FHB in the field at four locations in 2004. Between 26 and 135 progeny were tested from each variant. FHB severity and DON content were significantly reduced by all selection variants. The highest total selection gain was obtained by the three-step phenotypic selection for both traits, although marker-based selection for the two donor-QTL alleles from CM82036 proved to be more powerful on an annual basis. The large range of variation for FHB resistance and, to a lesser extent, DON content within the marker-based variant, however, shows that an additional phenotypic selection will enhance selection gain.