[Single-strand conformational polymorphism markers associated with a major QTL for fusarium head blight resistance in...

A major quantitative trait locus (QTL) associated with resistance to Fusarium head blight (FHB) was identified on chromosome 3BS between simple sequence repeat (SSR) markers Xgwm389 and Xgwm493 in wheat 'Ning 7840', a derivative from 'Sumai 3'. However, the marker density of SSR in the QTL region was much lower than that required for marker-assisted selection (MAS) and map-based cloning. The objective of this study was to exploit new markers to increase marker density in this QTL region by using single-strand conformational polymorphism (SSCP) markers developed from wheat expressed sequence tags (ESTs) on 3BS bin 8-0.78-1.0. Sixty-nine out of 85 SSCP primer pairs amplified PCR (polymerase chain reaction) products from the genomic DNA of 'Chinese Spring'. Thirty-four primer pairs amplified PCR products that could form clear ssDNA (single strand DNA) bands through denaturation treatment. Ten SSCP markers had polymorphisms between 'Ning 7840' and 'Clark'. Five of the ten polymorphic SSCP markers were located on chromosome 3B by nulli-tetrasomic analysis. Three SSCP markers (Xsscp6, Xsscp20, and Xsscp21) were mapped into the region between Xgwm493 and Xgwm533, and possessed higher coefficient of determination (R2) than Xgwm493 and Xgwm533. The SSCP markers, Xsscp6, Xsscp20, and Xsscp21, can be used for map-based cloning of the QTL and for marker-assisted selection in FHB resistance breeding.