硝态氮是旱地作物吸收氮素的主要形式,其吸收与硝酸盐转运蛋白(NRT)有重要的关系。本研究以玉米自交系B73 (V4版本)作为参考基因组,利用生物信息学方法鉴定了玉米ZmNRT基因家族成员,并从系统发育关系、GO (Gene Ontology)富集、基因结构和玉米不同时期及组织下的表达谱等方面全面解析玉米ZmNRT基因家族；并在氮诱导下,基于qPCR实验和共表达网络分析,对玉米ZmNRT家族基因在氮响应中的作用进行了系统的研究。结果表明,在玉米全基因组水平上共鉴定到162个ZmNRT基因,主要分为ZmNRT1 (62个) 和ZmNRT2 (100个) 两大类群。GO富集发现仅46个基因参与硝态氮转运过程,这些基因被不均等分成7个亚家族,每个家族1-15个基因。基因表达模式分析结果显示不同生育期和组织下ZmNRT基因表达是差异的。在氮诱导下,qPCR鉴定结果显示12个ZmNRT基因是氮响应基因,其中9个基因表达上调,3个基因表达下调；共表达网络结果发现,其中10个ZmNRT基因与已知的氮代谢基因存在显著共表达关系(|r|>0.8 p-value<0.05),推测这10个基因可能是调控玉米氮代谢的关键基因。该研究结果可为进一步分析玉米吸收和转运硝酸盐的关键基因的克隆及功能研究提供一定的参考。

Nitrate is the main form of nitrogen uptake by dryland crops, and its absorption is closely related to nitrate transporter (NRT). In this study, maize inbred line B73 (V4) was used as the reference genome to identify the members of maize ZmNRT gene family by using bioinformatic methods, from the aspects of phylogenetic relationship, GO (Gene Ontology) enrichment, gene structure and expression profiles. Under nitrogen induction, the role of ZmNRT family genes in nitrogen response in maize was systematically studied based on qPCR assay and co-expression network analysis. The results showed that a total of 162 ZmNRT genes were identified at the genome-wide level of maize, which were mainly divided into two groups, 62 ZmNRT1 genes and 100 ZmNRT2 genes. Then GO enrichment found that only 46 genes were involved in nitrate transport process, and these genes were unequally divided into 7 subfamilies with 1-15 genes, respectively. The result of gene expression pattern analysis indicated that ZmNRT gene expression differed in different growth stages and tissues. Under nitrogen induction, the qPCR results showed that 12 genes were nitrogen-responsive genes, of which 9 genes were up-regulated while 3 genes were down-regulated. Subsequently, through the co-expression network constructed, we found that 10 of the nitrogen responsive genes had significant co-expression relationships with annotated key genes of nitrogen metabolism (| r |>0.8, p-value<0.05), and speculated that these 10 genes might be the key genes of regulating nitrogen metabolism in maize. This study results will provide references for further analysis of the cloning and function of ZmNRT family genes, which are vital to nitrate uptake and transport in maize.

国家重点研发计划项目(2017YFD0102005)、江苏省农业科技自主创新资金 [CX(20)1002]