Previous studies have suggested that the maintenance of redox homeostasis is essential for plant growth. Here we investigated how redox homeostasis and signalling is modulated in response to different nitrogen (N) forms in tea plant roots. Our results showed that both N deficiency and nitrate (NO₃^–) can trigger the production of hydrogen peroxide and lipid peroxidation in roots. In contrast, these responses were not altered by NH₄⁺. Further, N deficiency and NO₃^–-triggered redox imbalance was re-established by increased of proanthocyanidins (PAs) and glutathione (GSH), as well as upregulation of representative antioxidant enzyme activities and genes. To further explore the molecular bases of these responses, comparative transcriptome analysis was performed, and redox homeostasis-associated differentially expressed genes (DEGs) were selected for bioinformatics analysis. Most of these genes were involved in the flavonoid biosynthesis, GSH metabolism and the antioxidant system, which was specifically altered by N deficiency or NO₃^–. Moreover, the interplay between H₂O₂ (generated by RBOH and Ndufab1) and hormones (including abscisic acid, auxin, cytokinin and ethylene) in response to different N forms was suggested. Collectively, the above findings contribute to an understanding of the underlying molecular mechanisms of redox homeostasis and signalling in alleviating oxidative stress in tea plant roots.

先前的研究表明，氧化还原稳态对植物的生长至关重要。在这里，我们研究了茶树根中不同的氮（N）形式响应如何调节氧化还原稳态和信号传导。我们的结果表明，缺氮和硝酸盐（NO ₃ ^- ）可以触发生产过氧化氢和在根中的脂质过氧化的。相反，这些响应没有被NH ₄ ⁺改变。此外，氮缺乏和NO ₃ ^–通过增加原花青素（PAs）和谷胱甘肽（GSH）以及上调代表性的抗氧化酶活性和基因，重新建立了触发的氧化还原失衡。为了进一步探索这些反应的分子基础，进行了比较转录组分析，并选择了氧化还原稳态相关的差异表达基因（DEG）进行生物信息学分析。大多数这些基因的参与了类黄酮合成，GSH代谢和抗氧化系统，它是专门用N缺乏或改变NO ₃ ^- 。此外，H ₂ O ₂之间的相互作用建议由RBOH和Ndufab1产生）和激素（包括脱落酸，生长素，细胞分裂素和乙烯）对不同的N形式有反应。总的来说，以上发现有助于理解氧化还原稳态和减轻茶树根部氧化应激的信号传导的潜在分子机制。