Anjum Naser A, Gill Sarvajeet S, Gill Ritu, Hasanuzzaman Mirza, Duarte Armando C, Pereira Eduarda, Ahmad Iqbal, Tuteja Renu, Tuteja Narendra
Centre for Environmental and Marine Studies (CESAM) and Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal,
Protoplasma. 2014 Nov;251(6):1265-83. doi: 10.1007/s00709-014-0636-x. Epub 2014 Mar 29.
The enhanced generation of reactive oxygen species (ROS) under metal/metalloid stress is most common in plants, and the elevated ROS must be successfully metabolized in order to maintain plant growth, development, and productivity. Ascorbate (AsA) is a highly abundant metabolite and a water-soluble antioxidant, which besides positively influencing various aspects in plants acts also as an enigmatic component of plant defense armory. As a significant component of the ascorbate-glutathione (AsA-GSH) pathway, it performs multiple vital functions in plants including growth and development by either directly or indirectly metabolizing ROS and its products. Enzymes such as monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) and dehydroascorbate reductase (DHAR, EC 1.8.5.1) maintain the reduced form of AsA pool besides metabolically controlling the ratio of AsA with its oxidized form (dehydroascorbate, DHA). Ascorbate peroxidase (APX, EC 1.11.1.11) utilizes the reduced AsA pool as the specific electron donor during ROS metabolism. Thus, AsA, its redox couple (AsA/DHA), and related enzymes (MDHAR, DHAR, and APX) cumulatively form an AsA redox system to efficiently protect plants particularly against potential anomalies caused by ROS and its products. Here we present a critical assessment of the recent research reports available on metal/metalloid-accrued modulation of reduced AsA pool, AsA/DHA redox couple and AsA-related major enzymes, and the cumulative significance of these antioxidant system components in plant metal/metalloid stress tolerance.
在金属/类金属胁迫下，植物中活性氧（ROS）的生成增强是最为常见的现象，而升高的ROS必须被成功代谢，以维持植物的生长、发育和生产力。抗坏血酸（AsA）是一种含量丰富的代谢产物和水溶性抗氧化剂，它除了对植物的各个方面产生积极影响外，还是植物防御体系中一个神秘的组成部分。作为抗坏血酸-谷胱甘肽（AsA-GSH）途径的重要组成部分，它在植物中发挥着多种重要功能，包括通过直接或间接代谢ROS及其产物来促进生长和发育。诸如单脱氢抗坏血酸还原酶（MDHAR，EC 1.6.5.4）和脱氢抗坏血酸还原酶（DHAR，EC 1.8.5.1）等酶，除了在代谢上控制AsA与其氧化形式（脱氢抗坏血酸，DHA）的比例外，还维持AsA库的还原形式。抗坏血酸过氧化物酶（APX，EC 1.11.1.11）在ROS代谢过程中利用还原的AsA库作为特定的电子供体。因此，AsA、其氧化还原对（AsA/DHA）以及相关酶（MDHAR、DHAR和APX）共同形成了一个AsA氧化还原系统，以有效地保护植物，特别是抵御由ROS及其产物引起的潜在异常情况。在此，我们对最近有关金属/类金属积累对还原AsA库、AsA/DHA氧化还原对和AsA相关主要酶的调节作用的研究报告进行了批判性评估，以及这些抗氧化系统成分在植物对金属/类金属胁迫耐受性中的累积意义。
