Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants (CIMAP), Lucknow, 226015, India; Academy of Scientific and Innovative Research (AcSIR), AcSIR Campus, CSIR-Human Resource Development Centre Campus, Sector-19, Kamla Nehru Nagar, Ghaziabad, 201002, U.P., India.
Department of Biochemistry, Central University of Haryana, Mahendergarh, Haryana, 123031, India.
Plant Physiol Biochem. 2019 Jun;139:620-629. doi: 10.1016/j.plaphy.2019.03.040. Epub 2019 Mar 30.
Being static, plants are frequently exposed to various essential and non-essential heavy metals from the surroundings. This exposure results in considerable ROS generation leading to oxidative stress, the primary response of the plants under heavy metal stress. Withania somnifera is a reputed Indian medicinal plant in Ayurveda, having various pharmacological activities due to the presence of withanolides. The present study deals with the understanding endurance of oxidative stress caused by heavy metal exposure and its management through antioxidant partners in synchronization with secondary metabolites in W. somnifera. The quantitative assessment of enzymatic/non-enzymatic antioxidants revealed significant participation of ascorbate-glutathione-α-tocopherol triad in ROS management. Higher activities of glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) resulted in glutathione and ascorbate accumulation. In addition, superoxide dismutase (SOD), glutathione peroxidase (GPX) and peroxidase (POD) were contributed considerably in ROS homeostasis maintenance. In-situ localization and assays related to ROS generation/scavenging revealed key management of ROS status under Cd stress. Higher antioxidative and reducing power activity attributed to the tolerance capability to the plant. Increased expression of withanolide biosynthetic pathway genes such as WsHMGR, WsDXS, WsDXR and WsCAS correlated with enhanced withanolides. The present study indicated the crucial role of the ascorbate-glutathione-α-tocopherol triad in co-ordination with withanolide biosynthesis in affording the oxidative stress, possibly through a cross-talk between the antioxidant machinery and secondary metabolite biosynthesis. The knowledge may be useful in providing the guidelines for developing abiotic stress resistance in plants using conventional and molecular approaches.
作为静态生物，植物经常会从周围环境中吸收各种必需和非必需的重金属。这种暴露会导致大量活性氧（ROS）的产生，从而引发氧化应激，这是植物在重金属胁迫下的主要反应。睡茄是印度阿育吠陀医学中的一种著名药用植物，由于其含有茄属生物碱，因此具有多种药理学活性。本研究旨在了解植物对重金属暴露引起的氧化应激的耐受能力，并通过抗氧化剂伴侣与次生代谢物协同作用来管理这种应激。对酶/非酶抗氧化剂的定量评估表明，抗坏血酸-谷胱甘肽-α-生育酚三体系在 ROS 管理中具有重要作用。较高的谷胱甘肽还原酶（GR）、单脱氢抗坏血酸还原酶（MDHAR）和脱氢抗坏血酸还原酶（DHAR）活性导致谷胱甘肽和抗坏血酸的积累。此外，超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GPX）和过氧化物酶（POD）在 ROS 动态平衡维持中也有重要贡献。与 ROS 产生/清除相关的原位定位和测定表明，在 Cd 胁迫下，ROS 状态得到了关键管理。较高的抗氧化和还原能力归因于植物的耐受能力。茄属生物碱生物合成途径基因（如 WsHMGR、WsDXS、WsDXR 和 WsCAS）的表达增加与茄属生物碱的增强相关。本研究表明，抗坏血酸-谷胱甘肽-α-生育酚三体系与茄属生物碱生物合成的协同作用在抵御氧化应激方面起着至关重要的作用，这可能是通过抗氧化剂机制与次生代谢物生物合成之间的交叉对话实现的。这些知识可能有助于为利用常规和分子方法在植物中开发非生物胁迫抗性提供指导。
