Yan Lei, Lu Mu, Riaz Muhammad, Tong Kaiqing, Yu Hualong, Gao Guang, Niu Yusheng
Institute of Biomedical Engineering, College of Life Sciences, Qingdao University, Qingdao 266071, China.
Guangdong Engineering and Technology Center for Environmental Pollution Prevention and Control in Agricultural Producing Areas, College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
Ecotoxicol Environ Saf. 2025 Apr 1;294:118012. doi: 10.1016/j.ecoenv.2025.118012. Epub 2025 Mar 11.
Soil salinization has emerged as a major factor negatively affecting soil quality and plant productivity. Proline, functioning as an osmotic regulator, has been proposed as an effective strategy for enhancing plant tolerance to salt stress. This study aimed to investigate the effects of exogenous proline on salt tolerance in soybeans. A hydroponic experiment was conducted with different salt treatments (without NaCl, -NaCl; with 100 mM NaCl, +NaCl) and with or without 150 mM proline (+Pro, -Pro). The results showed that proline application alleviated salt stress-induced reductions in plant growth, photosynthetic parameters, and chlorophyll content while aiding recovery from leaf chlorosis. Proline treatment improved ion homeostasis by reducing Na levels and increasing K and Ca contents in the leaves. Salt stress increased malondialdehyde (MDA) and reactive oxygen species (ROS) levels, along with leaf peroxidase (POD) and catalase (CAT) activities, while decreasing superoxide dismutase (SOD) activity. Moreover, salt stress obviously enhanced proline accumulation, accompanied by increases in glutamate (Glu), glutamate-1-semialdehyde (GSA), and pyrroline-5-carboxylate (P5C) content, as well as the activities of pyrroline-5-carboxylate synthase (P5CS) and pyrroline-5-carboxylate reductase (P5CR) in the glutamate pathway, while reducing proline dehydrogenase (ProDH) activity. Exogenous proline treatment further elevated proline content and increased key substances and enzyme activities in both the glutamate (Glu and P5C content, P5CS and P5CR activity) and ornithine (Orn content and OAT activity) pathways while also reducing ProDH activity. Collectively, our results revealed that exogenous proline contributed to an attenuation of salt stress in soybeans by regulating both the glutamate and ornithine pathways to stimulate endogenous proline accumulation, mediate Na/K homeostasis, and inhibit oxidative damage.
土壤盐渍化已成为负面影响土壤质量和植物生产力的主要因素。脯氨酸作为一种渗透调节剂，已被提出是增强植物耐盐胁迫能力的有效策略。本研究旨在探究外源脯氨酸对大豆耐盐性的影响。进行了一项水培实验，设置不同的盐处理（无氯化钠，-NaCl；添加100 mM氯化钠，+NaCl）以及添加或不添加150 mM脯氨酸（+Pro，-Pro）。结果表明，施用脯氨酸减轻了盐胁迫导致的植物生长、光合参数和叶绿素含量的降低，同时有助于从叶片黄化中恢复。脯氨酸处理通过降低叶片中的钠含量并增加钾和钙含量，改善了离子稳态。盐胁迫增加了丙二醛（MDA）和活性氧（ROS）水平，以及叶片过氧化物酶（POD）和过氧化氢酶（CAT）活性，同时降低了超氧化物歧化酶（SOD）活性。此外，盐胁迫明显增强了脯氨酸积累，同时谷氨酸（Glu）、谷氨酸-1-半醛（GSA）和吡咯啉-5-羧酸（P5C）含量增加，以及谷氨酸途径中吡咯啉-5-羧酸合成酶（P5CS）和吡咯啉-5-羧酸还原酶（P5CR）的活性增加，而脯氨酸脱氢酶（ProDH）活性降低。外源脯氨酸处理进一步提高了脯氨酸含量，并增加了谷氨酸（Glu和P5C含量、P5CS和P5CR活性）和鸟氨酸（Orn含量和OAT活性）途径中的关键物质和酶活性，同时也降低了ProDH活性。总体而言，我们的结果表明，外源脯氨酸通过调节谷氨酸和鸟氨酸途径来刺激内源性脯氨酸积累、介导钠/钾稳态并抑制氧化损伤，从而有助于减轻大豆的盐胁迫。
