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.