| Pre-harvest sprouting (PHS) in wheat is a worldwide balefulness which severely reduces yield and end-use quality, resulting in substantial economic losses. PHS is a serious problem in many countries included China. Breeding new cultivar resistant to PHS is one of the top topics for the international and domestic. Therefore, identification of new resistance genes and their tightly linked molecular markers as well as gene pyramiding by molecular assisted selection (MAS) would achieve the aim of developing new resistant cultivar, which plays a key role in guarantee the quality and production of wheat in China. The aims of this study were to map QTLs of PHS resistant wheat line CA0431and find the molecular markers linked with the resistant genes which could be used for MAS, and use the F4lines derived from Zhongyou206/CA9550//Zhongyou206to validate the effect of MAS with Vp1Bb associated with PHS, which might be usful for breeding new PHS resistant line or variety. The main results as follows:1.220F2individual plants and the corresponding F23lines derived from a cross between PHS resistant line CA0431and PHS susceptible cultivar Zhongyou206with high quality and strong gluten were used for PHS testing and QTL analysis. A total of1,444molecular markers were used to screen the parents, and31markers with polymorphisms between the resistant and susceptible bulks were used to genotype the entire F2population. The31markers were distributed on nine linkage groups, covering a genetic distance of383cM. Broad-sense heritability of sprouting rate was0.71across environments. Inclusive composite interval mapping (ICIM) identified four QTLs distributed on chromosome2B and3A, which were designated as QPhs.caas-2BL, QPhs.caas-3AS, QPhs.caas-3A and QPhs.caas-3AL, each explaining7.7-9.9%,11.8-27.7%,2.8-16.3%and4.1-5.6%of the phenotypic variance, respectively. And the four QTLs, accounting for32.3-55.1%of phenotypic variance in a simultaneous fit across three environments. All the four QTLs came from the parent CA0431, and among them, QPhs.caas-3AS, with a major effect on PHS resistance, was stable across all environments. QPhs.caas-2BL, a novel QTL with a stable effect on PHS resistance, was flanked by Xbarc1042and Xmag3319. The intervals between the flanking markers of the two QTLs were small, which suggest that the two QTLs and their linked molecular markers could be useful for marker-assisted selection in wheat breeding programs.2. White-grained wheat line CA9550with a good resistance to PHS was bred by our group, and its genotype is Vp-1Bbb. The markers of Vp-1Bb was used for MAS in the F1population derived from Zhongyou206/CA9550//Zhongyou206, and in the following three generations of selfing, populations were selected according to integrated agronomic traits. The90F4lines were used for PHS test and validation the effect of Vp-1Bb MAS. The average sprouting rate of the lines with the Vp-1Bbb genotype was the lowest. However, the difference of the mean sprouting rate value between the Vp-1Bbb genotypes and CA9550was quite larger. It indicated that the resistance of CA9550was not only controlled by Vp-1Bb gene, but also commanded by other gens. The fact seemed that it was not highly effective by MAS for improve PHS resistance if only one or two molecular markers were used. |
