Correlation Of SNP On Chromosome 3B With Agronomic Trait And Validation Of QTL QSn.nau-5A Controlling Tiller Number In Wheat

Nanda2419 is one of the most important founder parents for wheat breeding in china,which has excellent agronomic traits and combining ability,and has been used to breed 130 varieties of derivatives.In order to analyze the contribution of the Nanda2419-type allele in the derived cultivars,the whole genome-scanning using 90K iSelect SNP chip was carried out from generation 1 to 4 in Nanda2419 derived lines,the association analysis was conducted between agronomic trait and 829 SNPs on chromosome 3B in mini-core collection,and the genetic effect of Nanda2419-type alleles was also analyzed.Additionally,the QSn.nau-5A on chromosome 5A controlling tiller numbers mapped by ND2419 and WSB recombinant inbred lines was validated,the results are listed as follows:1.74 SNPs significantly associated with flag leaf width,grain weight,plant height,heading date were detected on chromosome 3B by genome-wide association analysis in 125 materials of mini-core collection populations,some of which are pleiotropic,and the agronomic performance of Nanda2419-type alleles is excellent at the most SNP sites.2.The whole genome-scanning was conducted in Nanda-derived lines,finding that the frequency of Nanda2419-type alleles of 306 SNPs and 88 SNPs are significantly higher and lower than that in mini-core collection population,respectively(P=0.001).The number of SNPs of Nanda2419-type alleles under positive selection is 3.5 times as that under negative selection.3.The transmission of 74 SNPs significantly associated with agronomic traits can be classified into three categories.First type:Nanda2419-type alleles are elite allelic variation,its transmission frequency has an increasing trend in the offspring,this type totally has 60 SNPs.Second type:Nanda2419-type alleles are non-elite alleles,the transmission frequency reduced significantly in the offspring,this type totally has 6 SNPs.Third type:some SNPs significantly associated with agronomic trait,but their transmission frequency does not change signicantly in 2419 derived lines,this type totally has 8 SNPs.This result further demonstrated that the majority of the Nanda2419-type alleles are excellent.4.The transmission frequency of Nanda2419-type alleles of 755 SNPs not associated with investigated trait in Nanda2419-derived lines can also be classified into three types above,among them,77.5%SNP sites does not change significantly;and 14.3%and 8.2%SNP sites shows increased and decreased significantly in the derived lines,respectively.5.In this study,the QSn.nau-5A controlling tiller numbers mapped by ND2419 and WSB recombinant inbred lines was also introduced into cultivars Zhengmai 9023 and Yangmai 17,respectively,two near isogenic lines were constructed.Comparing with the recurrent parent,the productive tiller numbers of the near isogenic lines increased by 3.75 and 2.9 respectively.For mapping this QTL more accurately,the recombinant screening in the interval was also conducted,7 and 14 types of homozygous recombinants were obtained for Zhengmai 9023 and Yangmai 17 background,respectively.