The Impact of Nitrogen and Phosphorus Interaction on Growth, Nutrient Absorption, and Signal Regulation in Woody Plants.

This article methodically reveals how, in woody plants (poplar), the interaction between N and P coordinates root structure and nutrient absorption through a complex hormone signaling network. This study bridges a significant gap in our knowledge of nutrient interaction networks. The results demonstrate that NO significantly enhances the gene expression and enzymatic activity of organic acid synthases (MDH, PEPC) and APs. Furthermore, it synergizes with IAA/ABA signals to refine root structure, enhancing the surface area for P absorption. In low Pi availability environments, NO further promotes P recycling by simultaneously boosting the levels of Pi transport proteins (notably, the PHO family), facilitating myo-inositol phosphate metabolism (via IMP3/ITPK1-mediated PP-InsPs degradation), and augmenting IAA/SA signals. Pi induces the activity of N assimilation enzymes (GS/GOGAT/GDH), facilitating nitrogen metabolism. However, in the absence of N, it leads to a metabolic imbalance characterized by high enzymatic activity but low efficiency. Alternatively, adequate N availability allows Pi to improve root robustness and N assimilation efficiency, mediated by IAA/GA accumulation and ABA signaling (e.g., /). We propose the existence of an intricate network in poplar, orchestrated by transcriptional cascades, metabolic regulation, and hormonal synergism. Key modules such as -, , , and are likely central to this network's function. These findings offer a foundational framework for the development of molecular breeding and precise fertilization strategies, enhancing the efficient use of N and P in forestry.