Scholarlink

Background <p>Root exudates play a crucial role in regulating nitrogen (N) availability in the rhizosphere. However, how specific exudate components mediate soil N cycling processes via microbial communities remains poorly understood.</p> Results <p>In a cotton field experiment with four N application rates (N1: 330, N2: 281, N3: 231, N4: 0&#xa0;kg·ha⁻¹), we employed in-situ collection and metabolomic analysis of root exudates and identified thiamine and L-lysine as key components induced under N reduction. Using a rhizosphere microcosm system, we demonstrated that in response to mild N reduction (N2), thiamine recruited functional microbes such as Alphaproteobacteria and <i>Cephalotrichum</i>, thereby enhancing β-glucosidase activity. This ‘C–N coupling’ strategy coordinates soil C decomposition and N transformation via recruited functional microbes, increased soil dissolved inorganic N (DIN) by 27.1% and the net N mineralization rate (NMR) by 18.8%. Under more moderate N reduction (N3), L-lysine stimulated N-cycling bacteria including Methylomirabilota and Myxococcota, synergistically activated β-1,4-N-acetylglucosaminidase and urease, and enhanced organic N mineralization. This ‘direct N activation’ strategy directly hydrolyzes organic N substrates without relying on C coupling, markedly increased soil DIN by 73.8% and NMR by 12.4%.</p> Conclusion <p>Our findings reveal that specific root-derived metabolites, thiamine and L-lysine, orchestrate distinct microbial mechanisms to sustain N availability under different N reduction scenarios. This study provides novel insights into plant–microbe–nutrient feedbacks and identifies potential metabolic targets for improving N use efficiency in agroecosystems.</p> Graphical Abstract <p></p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Microbial mechanisms of rhizosphere nitrogen cycling mediated by cotton root exudates under nitrogen reduction: roles of thiamine and L-lysine

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年1月28日

查看全文
  • Zihui Shen,
  • Yunzhu He,
  • Hushan Wang,
  • Mengjuan Liu,
  • Jiaqiang Zhu,
  • Yao Yang,
  • Xinmin Luan,
  • Wangfeng Zhang,
  • Xiaozhen Pu

摘要

Background

Root exudates play a crucial role in regulating nitrogen (N) availability in the rhizosphere. However, how specific exudate components mediate soil N cycling processes via microbial communities remains poorly understood.

Results

In a cotton field experiment with four N application rates (N1: 330, N2: 281, N3: 231, N4: 0 kg·ha⁻¹), we employed in-situ collection and metabolomic analysis of root exudates and identified thiamine and L-lysine as key components induced under N reduction. Using a rhizosphere microcosm system, we demonstrated that in response to mild N reduction (N2), thiamine recruited functional microbes such as Alphaproteobacteria and Cephalotrichum, thereby enhancing β-glucosidase activity. This ‘C–N coupling’ strategy coordinates soil C decomposition and N transformation via recruited functional microbes, increased soil dissolved inorganic N (DIN) by 27.1% and the net N mineralization rate (NMR) by 18.8%. Under more moderate N reduction (N3), L-lysine stimulated N-cycling bacteria including Methylomirabilota and Myxococcota, synergistically activated β-1,4-N-acetylglucosaminidase and urease, and enhanced organic N mineralization. This ‘direct N activation’ strategy directly hydrolyzes organic N substrates without relying on C coupling, markedly increased soil DIN by 73.8% and NMR by 12.4%.

Conclusion

Our findings reveal that specific root-derived metabolites, thiamine and L-lysine, orchestrate distinct microbial mechanisms to sustain N availability under different N reduction scenarios. This study provides novel insights into plant–microbe–nutrient feedbacks and identifies potential metabolic targets for improving N use efficiency in agroecosystems.

Graphical Abstract