A DUF630 and 632 Domains-containing Protein, ZmNRL1, Acts as a Positive Regulator of Nitrogen Stress Response in Maize.

Nitrogen (N) is a key macronutrient whose availability often determines maize growth and productivity. Improving nitrogen use efficiency (NUE) is critical to increase maize yield while reducing N input, and more importantly, alleviating environmental pollution. However, only a few genes have been exploited for maize NUE improvement thus far. Here, we identified 44 candidate genes associated with NUE-related traits by performing a genome-wide association analysis in a maize natural population. We further found that the natural variations in ZmNRL1, encoding a DUF630 and DUF632 domains-containing protein, strongly associated with chlorophyll content under N starvation. Loss function of ZmNRL1 reduced nitrogen content and weakened plant growth under hydroponic and soil conditions, whereas overexpression of ZmNRL1 conferred better tolerance to N stress and elevated yields in transgenic maize and Arabidopsis. Comparative transcriptome analysis further revealed that ZmNRL1 has a broad impact on the expression of many N utilization and signaling genes. Moreover, we showed that ZmNRL1 anchored to the plasma membrane likely through the dual lipid modifications of myristoylation and palmitoylation. Thus, we propose that ZmNRL1 is a key regulator of the adaptation response to N limitation in maize and could be a potential target for breeding high-yield maize with enhanced NUE.