Nitric oxide cross-talks during low-temperature stress in plants.

Nitric oxide (NO) is a crucial signaling molecule, playing a pivotal role in response to low-temperature (LT) stress in plants. NO mediates cold acclimation mainly via modulation of redox homeostasis, phytohormone signaling, calcium signaling, transcription factors, and other secondary messengers. This review explores the intricate dialogue between NO and various plant growth regulators. NO cross-talk with phytohormones like ethylene, abscisic acid, brassinosteroids, melatonin and salicylic acid, mitigates chilling injuries and alleviates physiological damage during LT. Secondary metabolites such as polyamines engage with NO in a reciprocal regulation and play synergistic role in NO-mediated stress tolerance. These cross-talks maintains redox homeostasis via upregulation of antioxidant enzymes and modulation of enzymes involved in Asada-Halliwell pathway. ALA and GABA are non-protein amino acids that are involved in NO-mediated LT stress tolerance. NO interacts with calcium signaling pathways through Cold-Responsive Protein Kinase 1 (CRPK1) and C-repeat binding factors (CBF) regulatory network to induce stress response. Also, NO cross-talks with mitogen-activated protein kinases (MPKs), enhancing nitrate reductase (NR) activity. Phytochrome-mediated NO signaling plays a role in activating ICE-CBF-COR regulon under freezing tolerance. Moreover, recent advances reveal that NO modulates microRNA expression to regulate cold-responsive genes. Despite substantial progress, the precise molecular interactions between NO and these signaling pathways remain partially understood. Future research should focus on elucidating these mechanisms to develop NO-based strategies for improving crop resilience in cold environments.