外源尿素缓解烟草生长受铵毒的生物学机制初探

A Preliminary Study on the Biological Mechanisms Underlying the Alleviation of Ammonium Toxicity-Induced Growth Inhibition in Tobacco by Exogenous Urea

摘要: 本研究聚焦植物铵毒现象及其作用机理这一农业科学与生物学领域长期关注且亟待突破的基础理论问题。以模式植物烟草为材料，研究发现，在含3 mM $N{H}_4^{+}$ 的水培条件下，烟草生长受到显著抑制；而添加微摩尔浓度的外源尿素后，烟草地上部和地下部生物量、侧根数量及总根长均显著增加，表明外源尿素能够有效缓解铵离子对烟草生长造成的胁迫。进一步分析表明，该缓解过程伴随着精氨酸、一氧化氮、精胺和亚精胺等信号物质水平的变化，提示其可能通过调控相关信号代谢网络参与烟草对铵毒胁迫的响应过程。

Abstract: Ammonium toxicity and its underlying mechanisms are long-standing fundamental issues in agricultural science and biology that have attracted sustained attention and urgently require further investigation. Using tobacco as a model plant, this study found that tobacco growth was significantly inhibited under hydroponic conditions containing 3 mM $N{H}_4^{+}$ . However, the addition of exogenous urea at micromolar concentrations significantly increased shoot and root biomass, lateral root number, and total root length, indicating that exogenous urea can effectively alleviate the growth stress caused by ammonium in tobacco. Further analysis showed that this alleviating process was accompanied by changes in the levels of signaling molecules such as arginine, nitric oxide, spermine, and spermidine, suggesting that exogenous urea may participate in the tobacco response to ammonium toxicity by regulating related signaling and metabolic networks.