Proline plays adaptive roles in plant tolerance to cadmium (Cd)-induced stress, but many gaps remain to be elucidated as the responses triggered by exogenously supplied proline or endogenously overproduction are not well known. Thus, we assayed the nutritional status, metabolite profiling, and antioxidative responses in wild type and transgenic tobacco (Nicotiana tabacum L.) containing the P5CSF129A gene under control of the cauliflower mosaic virus (CaMV35S) or stress inducible rd29A promoters. The plants were exposed or unexposed to Cd (0 and 50 μmol L⁻¹ CdCl₂·H₂O) for 24 and 72 h. The wild type plants were also treated with or without exogenous proline (1 mmol L⁻¹). Plants supplied with exogenous proline exhibited lower Cd translocation from roots to leaves than plants overproducing proline, avoiding oxidative damages in the leaves of these plants. Meanwhile, tobacco overproducing proline was less susceptible to Cd-induced nutritional changes than wild type plants and presented better metabolic adjustment under Cd exposure compared to plants supplied with exogenous proline. Plants overproducing proline increased the synthesis of sugars and organic acids under Cd exposure, which contributed to absence of oxidative stress, since both superoxide dismutase and catalase were not active against Cd-induced oxidative stress in these genotypes. Plants overproducing proline under the control of rd29A presented higher proline concentration in comparison to the CaMV35S promoter. With exception of rd29A plants that presented high proline and reduced glutathione (GSH) concentrations, the other plants presented an inverse correlation between proline and GSH synthesis after 72 h of Cd exposure.

脯氨酸在植物对镉 (Cd) 诱导的胁迫耐受中发挥适应性作用，但由于外源供应脯氨酸或内源性生产过剩引发的反应尚不清楚，因此许多差距仍有待阐明。因此，我们检测了含有P5CSF129A基因的野生型和转基因烟草（烟草）的营养状况、代谢物谱和抗氧化反应，这些烟草含有在花椰菜花叶病毒（CaMV35S）或应激诱导型 rd29A 启动子控制下的P5CSF129A基因。将植物暴露于或未暴露于 Cd（0 和 50 μmol L ^-1 CdCl ₂ ·H ₂ O）24 和 72 小时。野生型植物也用或不用外源脯氨酸（1 mmol L ^-1）。与过量生产脯氨酸的植物相比，供应外源脯氨酸的植物表现出从根到叶的 Cd 易位较低，避免了这些植物叶片的氧化损伤。同时，与提供外源脯氨酸的植物相比，烟草过量生产脯氨酸比野生型植物更不易受 Cd 诱导的营养变化影响，并且在 Cd 暴露下表现出更好的代谢调节。过量生产脯氨酸的植物在 Cd 暴露下增加了糖和有机酸的合成，这有助于不存在氧化应激，因为超氧化物歧化酶和过氧化氢酶在这些基因型中对 Cd 诱导的氧化应激没有活性。与 CaMV35S 启动子相比，在 rd29A 控制下过量生产脯氨酸的植物表现出更高的脯氨酸浓度。