Transcriptional regulation modulates nitrate uptake and utilization of Pinus elliottii under nitrogen stress

In natural and agricultural ecosystems, nitrogen deficiency is often a major limiting factor for plant growth, while research on the molecular genetic basis of nitrogen uptake and utilization in slash pine remains scarce. This study explored the regulatory mechanisms of pine needles under different conditions by comparing the differences in nitrogen response of needles from different slash pine families at different time points under varying nitrogen concentrations, aiming to better understand the expression profile of nitrogen uptake and utilization in slash pine needles. Three key results were obtained: (1) A total of 2353 differentially expressed genes were identified, mainly including transcription factors families, such as C3H, bHLH, MYB, and others. These genes have been reported to be associated with nitrogen uptake and utilization in plants. (2) The nitrogen uptake and utilization pathway contains 36 DEGs encoding 10 types of proteins. (3) Weighted Gene Co-expression Network Analysis showed a strong correlation between ground diameter of slash pine and module gene expression, and the hub gene Pee07g026510 exhibited high connectivity with other nitrogen metabolism genes. This confirms that Pee07g026510 can affect Diameter growth by regulating GAD expression-specifically, generating GABA to alleviate ammonium toxicity under high-nitrogen conditions and prioritizing the efficiency of the GS/GOGAT cycle under low-nitrogen conditions. This is consistent with the theory that nitrogen deficiency inhibits biomass accumulation, providing a fundamental reference for the management and genetic improvement of slash pine plantations.