Amino acid metabolism pathways as key regulators of nitrogen distribution in tobacco: insights from transcriptome and WGCNA analyses.

BACKGROUND AND AIM

Nitrogen (N) is crucial for plant growth and is distributed across various N morphologies within plant organs. However, the mechanisms controlling the distribution of these N morphologies are not fully understood. This study investigated key amino acid (AA) biosynthesis pathways regulating N distribution and their impact on plant physiology and growth.

METHODS

We examined N distribution in the leaves, stems, and roots of two tobacco cultivars (Hongda and K326) under different N treatments at 75, and 100 days after transplanting (DAT). Transcriptome analysis was performed at 75 and 100 DAT to explore N distribution and AA metabolism pathways. Weighted gene co-expression network analysis (WGCNA) identified pathways regulating N distribution, and the Mantel test assessed the impact of N treatments, growth stages, and cultivars on N distribution.

RESULTS

Statistically significant differences in N distribution were observed across environmental conditions, growth stages, cultivars, and plant organs (p < 0.05). WGCNA identified phenylalanine metabolism (ko00360), alanine, aspartate, and glutamate metabolism (ko00250), and glycine, serine, and threonine metabolism (ko00260) pathways regulating the distribution of N (sodium dodecyl sulfate insoluble N), N (water soluble N), and N (sodium dodecyl sulfate soluble N), respectively. Increased N application promoted N accumulation, while earlier growth stages and cultivar Hongda favored N distribution. N distribution was inhibited under high N conditions. Gene expression in these pathways correlated with N distribution, biomass, and N accumulation.

CONCLUSION

This study elucidates the mechanisms regulating N distribution in tobacco, emphasizing the role of AA metabolism pathways. These findings are essential for improving N utilization and optimizing N management practices, ultimately enhancing crop productivity and supporting sustainable agricultural practices.