Mapping Qtls For Enhancing Early Biomass Derived Fromaegilops Tauschiiin Synthetic Hexaploid Wheat

Strong early vigour plays a crucial role in wheat yield improvement by enhancing resource utilization efficiency. Synthetic hexaploid wheat (SHW) combines the elite genes of tetraploid wheat withAegilops tauschiiand has been widely used in wheat genetic improvement for its abundant genetic variation. The two SHWs Syn79 and Syn80 were derived from the crossing of the same tetraploid wheat DOY1 with two differentAe.tauschiiaccessions, AT333 and AT428, respectively. The Syn80 possessed better early vigour traits than Syn79, theretically caused by their D genome fromAe.tauschii. To dissect their genetic basis in a hexaploid background, 203 recombinant inbred lines (RILs) derived from the cross of Syn79 x Syn80 were developed to detect quantitative trait loci (QTL) for four early biomass related traits: plant height (PH), tiller number (TN), shoot fresh weight (SFW) and shoot dry weight (SDW) per plant, under five different environmental conditions. Determined from the data of SNP markers, two genome regions on 1DS and 7D were stably associated with the four early biomass related traits showing pleiotropic effects. Four stable QTLsQPh.saas-1DS,QTn.saas-1DS,QSfw.saas-1DSandQSdw.saas-1DSexplaining 7.92, 15.34, 9.64 and 10.15% of the phenotypic variation, respectively, were clustered in the region of 1DS fromAX-94812958toAX-110910133. Meanwhile,QPh.saas-7D,QTn.saas-7D,QSfw.saas-7DandQSdw.saas-7Dwere flanked byAX-109917900andAX-110605376on 7D, explaining 16.12, 24.35, 15.25 and 13.37% of the phenotypic variation on average, respectively. Moreover, these genomic QTLs on 1DS and 7D enhancing biomass in the parent Syn80 were fromAe.tauschiiAT428. These findings suggest that these two QTLs fromAe.tauschiican be expressed stably in a hexaploid background at the jointing stage and be used for wheat improvement.