Mining Favorable Alleles of QTLs Conferring 1000-Grain Weight from Synthetic Wheat

Abstract

In common wheat(Triticum aestivum L.),1000-grain weight(TGW) is an important component of grain yield.How-ever,TGW is generally negatively correlated with grain number per spike and spike number per plant and positively correlated with plant height.The aim of this study was to mine favorable alleles of QTLs conferring TGW from synthetic wheat using ad-vanced backcross QTL analysis.A BC5F2:3 population consisting of 85 lines were generated from a cross between Laizhou 953,a Chinese commercial wheat variety,and Am3,a synthetic hexaploid wheat,followed by backcrossing with Laizhou 953 as recur-rent parent and selfing.Three hundred and fourty-eight polymorphic SSR markers were used for genotyping.Using composite interval mapping(CIM),three major QTLs,QGw.caas-1A,QGw.caas-3D,and QGw.caas-4B,with alleles increasing TGW from Am3,were detected in at least two environments.They could explain phenotypic variations ranging from 10.90 to 33.79%.Among the three QTLs,the alleles originated from Am3 could increase 2.3–4.8 g of TGW without decreasing grain number or spike number,or two of them,even without increasing plant height.Using mixed-model composite interval mapping(MCIM),one QTL(QGw.caas-3D) was detected with no significant interactions across the environment.Moreover,the QTL was at the same interval as the common QTL detected in 3 environments with CIM method.It is suggested that QGw.caas-3D is insensitive to environments,and may be a stable and major QTL for TGW.