Nitrate signaling and use efficiency in crops

Nitrate (NO(3)(–)) is not only an essential nutrient but also an important signaling molecule for plant growth. Low nitrogen use efficiency (NUE) of crops is causing increasingly serious environmental and ecological problems. Understanding the molecular mechanisms of NO(3)(–) regulation in crops is crucial for NUE improvement in agriculture. During the last several years, significant progress has been made in understanding the regulation of NO(3)(–) signaling in crops, and some key NO(3)(–) signaling factors have been shown to play important roles in NO(3)(–) utilization. However, no detailed reviews have yet summarized these advances. Here, we focus mainly on recent advances in crop NO(3)(–) signaling, including short-term signaling, long-term signaling, and the impact of environmental factors. We also review the regulation of crop NUE by crucial genes involved in NO(3)(–) signaling. This review provides useful information for further research on NO(3)(–) signaling in crops and a theoretical basis for breeding new crop varieties with high NUE, which has great significance for sustainable agriculture.