Mapping and validation of scab resistance QTLs in the Nanda2419 x Wangshuibai population

Wangshuibai is an indigenous scab resistance germplasm originated from Jiangsu, China. To characterize the genetic basis of scab resistance in this germplasm, QTLs for type I and type II resistances were detected using a recombinant inbred line (RIL) population created by single seed descent from Nanda2419 x Wangshuibai and a molecular marker map of more than 4000 cM constructed using RAPD, SSR and STS markers. The major QTLs for type I resistance in Wangshuibai were mapped to chromosomes 4BL and 5AS, and those for type II resistance were mapped to chromosomes 3BS. In addition, a QTL on chromosome 2B showed association with both types of resistance. These QTLs were verified with QTL near-isogenic lines. We found, by mapping QTLs for agronomical traits in the same population, that on chromosomes 4BL and 5AS the scab resistance QTLs co-locatcd with QTLs for plant height, thousand grain weight or flag leaf width. However, these associations could be break down by recombinant selection. We concluded that Wangshuibai is a valuable scab resistance gene resources and marker assisted selection would be of great help for its better utilization.