| A major QTL with typeⅡresistance to scab on chromosome 3BS has been detected in a lot of scab-resistance QTL mapping studies. The Qfhs-3B had a strong effect and explained up to 60% of the phenotypic variation. In this study, near-isogenic lines (NILs) for Qfhs-3B were developed using elite line PH691 as the recurrent parent with the help of marker-assisted selection. Finally, five and two NILs carring scab-resistance alleles derived from Wangshuibai and Sumai No.3, respectively, were developed. These NILs showed much better resistance compared with the recurrent parent PH691, although there was not significant difference of scab resistance among these NILs. NILs with Qfhs-3B had significant average reduction of over 58% for NDS and over 63% for LDR. Morphologically all the developed NILs looked similar to PH691. There were not significant differences between NILs and the recurrent parent statistically for five investigated agronomic traits including plant height, spike length, flag leaf length, flag leaf width and hundred-grain weight.For precise mapping Qfhs-3B, a secondary F2 population was constructed by crossing the Wangshuibai Qfhs.nau-3B NIL developed previously and its recurrent parent Mianyang 99-323. Resistance evaluation indicated that the F1 plants were susceptible to scab and the ratio of resistance segregation in the F2 population fitted 1:3, which suggested that recessive resistance gene controlled resistance in this NIL. A total of 44 recombinants were selected in this population. In addition,40 recombinants without Qfhs.nau-6B were selected from 530 Nanda2419×Wangshuibai recombinant inbred lines (RIL) population. These recombinants had significant differentce in scab resistance performance, and could be classified into resistant and susceptible groups clearly. According to the genotype and phenotype of these recombinants, Qfhs.nau-3B was placed in a 1.5-cM Xbarc147.1-Xsts32 interval.To analysis the association of Qfhs-3B with the typeⅡresistance,193 accessions including 78 Sumai No.3 derivations and 115 Chinese micro core wheat collections were surveyed. We found that there might be two loci associated with scab resistance in the Xbarc147～Xbarc102 interval, one is closely linked to Xbarc147 and another is closely linked to Xgwm493. |
