Plant nitrogen nutrition: enhancing plant resilience to abiotic stresses.
Nitrogen (N) is not only an essential macronutrient for plant growth and development but also functions as a pivotal signaling molecule that orchestrates adaptive responses to various abiotic stresses, including acidic stress, aluminum toxicity, salinity, drought, and extreme temperatures. This review synthesizes recent advances in our understanding of the molecular mechanisms by which N signaling, mediated by different N forms (e.g., NH4+ and NO3-), integrates with core stress-response pathways. We specifically discuss the genetic crosstalk between N sensing and key signaling cascades, including abscisic acid (ABA) signaling, the salt overly sensitive (SOS) pathway, and reactive oxygen species (ROS) homeostasis. The review details how this integration modulates physiological and transcriptional reprogramming through central regulators such as NIN-like proteins (NLPs), calcineurin B-like protein (CBL)-interacting protein kinase (CIPK), and the target of rapamycin (TOR) kinase, ultimately optimizing the trade-off between growth and tolerance. By establishing a unified genetic and molecular framework, this review aims to provide a theoretical basis for developing novel strategies in precision N management and molecular breeding to synergistically enhance N use efficiency (NUE) and abiotic stress tolerance in crops.