The impact of herbicide applications during osmotic stress on plant metabolism is not yet well understood. In this study, the relationship between paraquat-induced oxidative stress (PQ) and polyethylene glycol-induced osmotic stress (PEG) was evaluated in terms of changes in proline and polyamine metabolisms. Metabolic changes were investigated in maize seedlings treated with PQ and PEG separately and PQ in combination with PEG. Relative to all treatments, the combination of PQ and PEG further increased damage to the membranes, hydrogen peroxide and proline content, reducing the water potential of the leaves. The PEG treatment significantly increased the putrescine and spermidine contents compared to all treatments, but did not significantly change the spermine content compared to controls and combinations. The expression of gene encoding pyrroline-5-carboxylate synthase increased after PQ treatment in combination with PEG compared to the singular stresses, while the expression of gene encoding proline dehydrogenase decreased. Gene expression levels of arginine decarboxylase and S-adenosylmethionine decarboxylase, responsible for polyamine biosynthesis, were highest in PEG-treated seedlings. Furthermore, the gene expression levels of polyamine oxidase and copper amine oxidase, which cause polyamine degradation, decreased in all treatments compared to the control. In conclusion, paraquat applied during osmotic stress may increase the H₂O₂ content and, therefore, further damage the maize seedling membrane. Increased membrane damage and production of H₂O₂ may play a role in the induction of genes coding for key enzymes in proline and polyamine metabolism pathways.

渗透胁迫期间除草剂应用对植物代谢的影响尚不清楚。在这项研究中，根据脯氨酸和多胺代谢的变化评估了百草枯诱导的氧化应激 (PQ) 和聚乙二醇诱导的渗透压 (PEG) 之间的关系。研究了分别用 PQ 和 PEG 处理以及 PQ 与 PEG 组合处理的玉米幼苗的代谢变化。相对于所有处理，PQ和PEG的组合进一步增加了对膜的损伤、过氧化氢和脯氨酸含量，降低了叶片的水势。与所有处理相比，PEG 处理显着增加了腐胺和亚精胺含量，但与对照和组合相比，没有显着改变精胺含量。基因编码的表达与单一胁迫相比，PQ 与 PEG 联合处理后pyrroline-5-carboxylate synthase增加，而编码脯氨酸脱氢酶的基因表达减少。负责多胺生物合成的精氨酸脱羧酶和S-腺苷甲硫氨酸脱羧酶的基因表达水平在 PEG 处理的幼苗中最高。此外，与对照相比，导致多胺降解的多胺氧化酶和铜胺氧化酶的基因表达水平在所有处理中均降低。总之，在渗透胁迫期间施用百草枯可能会增加 H ₂ O ₂含量，因此进一步损害玉米幼苗膜。增加的膜损伤和 H ₂ O ₂的产生可能在诱导编码脯氨酸和多胺代谢途径中关键酶的基因中起作用。