The transcription factor ZmNLP5 increases maize grain yield by regulating nitrogen assimilation genes

Nitrogen (N) is crucial for maize (Zea mays L.) growth, development and yield. Dysfunction of the maize NIN-like protein 5 (ZmNLP5) reduces N assimilation, but the precise mechanism by which ZmNLP5 modulates N metabolism and its contribution to agricultural applications are not well understood. In this study, our transcriptomic profiling and chromatin immunoprecipitation followed by sequencing (ChIP-seq) analyses reveal 581 ZmNLP5-modulated target genes. We confirmed that ZmNLP5 physically interacted and transactivated contributors to N assimilation, including ZmNRT1.1D, ZmNIR1.1, ZmNR2.1, ZmGS4, ZmAS1, and ZmLBD6. Overexpression of ZmNLP5 upregulated N metabolism genes, and enhanced the enzymatic activities of nitrate reductase and glutamine synthase. Furthermore, overexpressing ZmNLP5 increased grain yield under both normal-N and low-N conditions. Introgression of the overexpressed ZmNLP5 allele into Zhengdan 958 resulted in comparable yield increases in field trials. Our study unveiled that ZmNLP5 is a potential genetic target for increasing nitrogen use efficiency and grain yield in maize.