Amino acid metabolism pathways as key regulators of nitrogen distribution in tobacco: insights from transcriptome and WGCNA analyses
Shichen Li, Waqar Ahmed, Tao Jiang, Dehai Yang, Linyuan Yang, Xiaodong Hu, Meiwei Zhao, Xiaoxia Peng, Yingfen Yang, Wei Zhang, Mingmin Li, Zhengxiong Zhao
Abstract
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. 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. 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 Nin-SDS (sodium dodecyl sulfate insoluble N), NW (water soluble N), and NS (sodium dodecyl sulfate soluble N), respectively. Increased N application promoted Nin-SDS accumulation, while earlier growth stages and cultivar Hongda favored NW distribution. NS distribution was inhibited under high N conditions. Gene expression in these pathways correlated with N distribution, biomass, and N accumulation. 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.