Near-Isogenic Line Development And Precise Mapping Of Major Scab Resistance QTL Qfhi.nau-5A In Wheat

Fusarium head blight or scab, caused mainly by Fusarium graminearum Schwabe, is a destructive disease of wheat (Triticum aestivum) worldwide, result in great yield losses and poor grain quality. Deployment of scab-resistant varieties is the most economical and effective strategy to curb this disease, and the genetic resistance is the basis of scab resistance breeding. As two of the best scab-resistant germplasms in the world, Wangshuibai and Sumai No.3 were researched much more on their genetic basis of scab resistance.Scab resistance of wheat is controlled by multiple genes and has been classified into two types:Resistance to initial infection (TypeⅠ) and Resistance to spread within the spike (TypeⅡ). We have identified two major QTLs against Fusarium graminearum infection in Wangshuibai by genetic mapping. In this study, near-isogenic lines (NILs) for one of the QTLs, namely Qfhi.nau-5A were developed using elite lines PH691 and Mianyang 2000-1 as the recurrent parents with the help of marker-assisted selection. Using PIS (percentage of infected spikes) as the typeⅠresistance index, resistance performance of the NILs were significantly high than recurrent parent. Genetic diversity analysis of Qfhi.nau-5A interval among six cultivars showed Wangshuibai and Sumai No.3 had the same genetic content in Qfhi.nau-5A region and the resistant cultivars very different from susceptible cultivars in the interval of Xbarc180-Xgwm304-Xgwm293 and Xmag3794 locus.For precise mapping Qjhi.nau-5A, recombinant plants of three genetic background were evaluated for FHB reaction. Using recombinants from the Nanda2419×Wangshuibai RIL population, recombinants with Mianyang 2000-1 background, and recombinants with Mianyang 99-323 background, Qfhi.nau-5A was placed in the interval of Xmag781～Xwmc446, Xbarc180-Xmag3794 and Xgwm415-Xgwm304. The three interval overlap each other, we precise mapped Qfhi.nau-5A within a genetic distance of 0.3 cM flanked by GWM415 and GWM304. Using Chinese Spring deletion lines, Qfhi.nau-5A linked molecular markers was physically mapped on 5AS chromosome C-5AS1-0.75 bin. The development of near-isogenic lines and precise mapping of the Qfhi.nau-5A could be used in disease resistance genes pyramiding and marker-assisted selection in wheat breeding program.