Toxicity in aquatic plants, caused by excess ammonium in the environment, is an important ecological problem and active research topic. Recent studies showed the importance of the enzyme Glutamate Dehydrogenase (GDH) in detoxifying ammonium. However, these results mainly derived from species comparisons, hence some mechanisms may have been obscured due to species differences. Our recent finding that young leaves of Potamogeton lucens were less sensitive to ammonium enrichment, than mature leaves allowed us to study ammonium detoxification within a species. We found that, unlike mature leaves, ammonium-tolerant young leaves of P. lucens could assimilate ammonium mainly through GDH. There was a 38% increase of NADH-dependent GDH in 50 mg/L ammonium concentration compared with 0.1 mg/L. Therefore, this study confirms the hypothesis that the GDH pathway plays a major role in the detoxification of ammonium in freshwater macrophytes.

由环境中过量铵引起的水生植物毒性是一个重要的生态问题和活跃的研究课题。最近的研究表明谷氨酸脱氢酶 (GDH) 在解毒铵中的重要性。然而，这些结果主要来自物种比较，因此某些机制可能因物种差异而被掩盖。我们最近发现Potamogeton lucens 的幼叶对铵富集的敏感性低于成熟叶，这使我们能够研究一个物种内的铵解毒。我们发现，与成熟叶不同，P. lucens的耐铵幼叶主要通过GDH同化铵。与 0.1 mg/L 相比，50 mg/L 铵浓度下 NADH 依赖性 GDH 增加了 38%。因此，本研究证实了 GDH 途径在淡水大型植物中铵的解毒中起主要作用的假设。