Marker-assisted development of near-isogenic lines for scab resistance qtls of wheat

Fusarium head blight (FHB) or scab resistance in wheat is a complex quantitative trait. Near-isogenic lines (NILs) carrying single FHB resistance QTL are valuable genetic stocks for genetic analysis and breeding. In previous studies, we mapped type I resistance QTLs against initial penetration and type 11 QTLs against fungal spread within spikes in the Nanda2419 x Wangshuibai RIL population. Using the molecular markers linked to the QTLs, we have developed NILs for four of the FHB resistance QTLs by marker-assisted introgression into the susceptible line Mianyang99-323. Background examination indicated that the recipient genome contents of the NILs have reached over 98% after three generations of backcross. These NILs showed significantly better resistance than the recurrent parent, providing another piece of evidence for successful enhancement of scab resistance by marker-assisted selection.