Fine Mapping And Contig Construction Of Fhb5,aqtl Responsible For Wheat Fusarium Head Blight

Fusarium head blight(FHB),a devastating wheat disease worldwide,is mainly caused by Fusarium graminearum Schwabe that can produce deoxynivalenol(DON)posing a risk for human and animal health.FHB causes a great reduction of grain yield and quality of wheat,and the best strategy is to develop FHB-resistant cultivars.Through a previous study in our lab,we found a QTL responsible for capacity of anti-FHB invasion in the landrace Wangshuibai,and this QTL was further localized on the short arm of chromosome 5A.Fine mapping was then carried out,and it was mapped to an interval of 0.017-0.036 cM,between the markers GWM415 and WGRB0142.The interval was corrected as 0.056-0.057 cM and flanked by WGRB0390 and WGRB0415,based on analysis of newly screened homozygous recombinants and their phenotypes in multiple years as well as the sequence information available at present.Using the markers within the Fhb5 interval,BARC 117,GWM304,GWM415,WGRB0269,WGRB0914,WGRB0817,WGRB0222,WGRB0018,WGRB0286 and BARC180,we aimed to screen new recombinants in two secondary F2 populations with Mianyang99-323 and PH691 as the backgrounds.However,no new recombination types were found since the current interval is so small and located around the centromere,a cold region of recombination.In order to construct the contig of the Fhb5,a number of molecular markers located on each side of GWM415 were used to screen Wangshuibai BAC library,and a total of ten positive single-clones were identified.Furthermore,comparison of the sequences of the single clones obtained and the scaffold of wheat genome,Fhb5 was defined within a physical map of approximately 1000 kb.This study would be useful to clone the Fhb5 gene in the near future.