Improving the nitrogen use efficiency (NUE) may considerably increase maize yield and decrease the use of nitrogen (N) fertilizer. But the genetic basis of NUE in maize is still poorly understood. In this study, an association panel of 139 maize inbred lines genotyped with 50,790 single nucleotide polymorphism (SNP) was used to dissect the genetic basis of NUE-related traits by genome-wide association study (GWAS). NUE, N uptake efficiency (NupE), N utilization efficiency (NutE), grain N concentration (GNC), stover N concentration (SNC) and N harvest index (NHI) were estimated under two N levels. GWAS was performed using a fixed and random model circulating probability unification (FarmCUP) method. In total, 27 and 23 significant SNP-traits association signals were identified under normal and low N levels. In addition, 10 significant association signals were detected based on the traits relative value (normal N supply / low N supply) of two N levels. Further, 60 candidate genes were predicted for these traits base on linkage disequilibrium (LD) and low nitrogen transcriptome analysis of significant SNP regions. Among the candidate genes identified in this study, 66.7% involved in nitrogen compound metabolic process. Zm00001d025831 and Zm00001d004633 encoded ammonium transporter1 and transmembrane amino acid transporter family protein, respectively, may be important candidate genes for NUE. The markers identified in this study maybe has important significance and could be useful in molecular marker assisted selection in breeding of high-NUE maize varieties, and the candidate genes could deepen the understanding of the genetic basis of NUE.

提高氮的利用效率（NUE）可以显着提高玉米产量并减少氮（N）肥料的使用。但是，玉米中NUE的遗传基础仍然知之甚少。在这项研究中，通过全基因组关联研究（GWAS），使用基因分型为50,790个单核苷酸多态性（SNP）的139个玉米自交系的关联小组来分析NUE相关性状的遗传基础。在两个氮水平下估算了NUE，氮吸收效率（NupE），氮利用效率（NutE），籽粒氮浓度（GNC），秸秆氮浓度（SNC）和氮收获指数（NHI）。使用固定和随机模型循环概率统一（FarmCUP）方法执行GWAS。在正常和低氮水平下，总共鉴定出27和23个重要的SNP-性状关联信号。此外，根据两个N水平的特征相对值（正常N供应/低N供应）检测到10个重要的关联信号。此外，基于连锁不平衡（LD）和重要SNP区域的低氮转录组分析，预测了60个候选基因的这些性状。在这项研究中确定的候选基因中，有66.7％参与了氮化合物的代谢过程。Zm00001d025831和Zm00001d004633分别编码的铵转运蛋白1和跨膜氨基酸转运蛋白家族蛋白可能是NUE的重要候选基因。本研究中鉴定出的标记物可能具有重要意义，并可能在分子标记辅助选择中用于高NUE玉米品种的育种，候选基因可以加深对NUE遗传基础的了解。