QTL mapping for nitrogen use efficiency and agronomic traits at the seedling and maturity stages in wheat

Abstract

Wheat is one of the most important staple food crops in many parts of the world. Nitrogen (N) is often considered to be the most important mineral nutrient element for crop growth and development. Nitrogen use efficiency (NUE) comprises nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE). We constructed a high-density genetic map using a set of 184 recombinant inbred lines (RILs) derived from the cross ‘Tainong 18 × Linmai 6’ (TL-RILs). In this study, 14 seedling traits and 17 maturity traits related to NUE and agronomic traits of wheat were investigated using the TL-RILs under hydroponic culture trials with high N (HN), moderate N (MN) and low N (LN) levels in two time frames, and under field trials with HN and LN levels in two growing seasons. A total of 121 and 130 quantitative trait loci (QTLs) we detected at seedling and maturity stages, respectively. Of these, 47 relatively high-frequency QTLs (RHF-QTLs) and 16 QTL clusters were found. The most important cluster, C9, included morphological, biomass, yield, NUpE and NUtE traits at the same time. The contributions for most QTLs were high, with the highest contribution of 30.00%. Seventeen RHF-QTLs were detected in this cluster, and it showed a favorable relationship between the RHF-QTLs for breeding programs. The markers in the region of cluster C9 should be valuable in marker-assisted selection (MAS). The sequence of DArT marker D-3940950 in the C9 region was identified to the RhtB1 gene with the similarity of 100% by BLAST against the Chinese Spring genome (IWGSCv1.0). The correlation analysis suggested that the morphological/biomass traits and eight yield traits can be considered as the primary morphological indexes for the evaluation of NUE instead of using element determinations, and the outcomes make it easy to identify NUE on a large scale.