Screening And Analysis Of Recombinants In Fhb4region Associated With Resistance To Fusarium Infection In Wheat

Type I resistance against initial penetration is the host's first barrier to infection by Fusarium species and is important for FHB resistance breeding.In a previous study in our lab,we detected a major type I resistance QTL on chromosome 4B using Nanda2419 ×Wangshuibai RIL population,and precisely mapped it to a 1.7 cM Xhbg226?Xgwm149 interval using a secondary population created with near-isogenic line(NIL),and named Fhb4.The objective of this study was to screen more recombinants of the Fhb4 region,and demonstrate the inheritance of Fhb4-conferred resistance.To analysis the mode of inheritance of Fhb4,the percentage of diseased spikelets(PDS)data of a F2 population developed by crossing a homologous Fhb4 NIL with its recurrent parent Mianyang 99-323 was investigated.The results showed that the resistance of the F2 plants segregated in the 3:1 ratio,suggesting that Fhb4 was inherited like a single dominant gene.To further fine map Fhb4,209 heterozygous recombinants were obtained from a F2 population of 4316 plants derived from the Fhb4 NIL × Mianyang 99-323 using two flanking markers Xhbg226 and Xmag7237 tightly linked to Fhb4.96 of the recombination events occurred between markers Xhbg226 and Xmag7237,and 113 ones occurred between markers Xmag7237 and Xgwm149.The genetic distances between adjacent markers were 1.12 cM and 1.33 cM,respectively.Xmag7237 was between Xhbg226 and Xgwm149.207 homozygous recombinants were then obtained by surveying the selfed progenies of 102 heterozygous recombinants,and were used for resistance evaluation.These homozygous lines had significantly different FHB resistance performance and could be clearly classified into resistant or susceptible groups.Based on the genotypic and phenotypic data of these recombinants,Fhb4 was further mapped to Xhbg226?Xmag7237 interval.