Shining Light on Regulatory Networks Integrating Nitrogen Use and Photosynthesis

Nitrogen and light availability are well-known to influence photosynthesis, having both individual and synergistic effects. However, the regulatory interactions between these signaling pathways, especially the transcription factors that perceive and integrate these cues remain to be elucidated. Arabidopsis grown in a matrix of nitrogen and light treatments exhibited distinct physiological and transcriptomic responses. Notably, the effect of nitrogen dose on biomass, nitrogen use efficiency, carbon:nitrogen ratio, and gene expression was highly dependent on light intensity. Genes differentially expressed across the treatments were enriched for photosynthetic processes, including pentose-phosphate cycle, light-harvesting and chlorophyll biosynthesis. We identified bZIP and MYB-related family transcription factors as key regulators of photosynthesis, nitrogen assimilation, and light response using gene regulatory network analysis. The transcription factors unveiled in this study have the potential to unlock new strategies for enhancing photosynthetic activity and nutrient-use efficiency in plants. Overall design: Leaf discs were collected from Arabidopsis grown under different nitrogen and light treatments (4 nitrogen doses and 3 light levels). Eight replicates were collected for each treatment, along with biomass, photosynthetic parameters (chlorophyll fluorescence), pigment content and elemental composition.