Brassinosteroid Ameliorates Zinc Oxide Nanoparticles-Induced Oxidative Stress by Improving Antioxidant Potential and Redox Homeostasis in Tomato Seedling.
Brassinosteroid Ameliorates Zinc Oxide Nanoparticles-Induced Oxidative Stress by Improving Antioxidant Potential and Redox Homeostasis in Tomato Seedling.
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油菜素类固醇通过改善番茄幼苗的抗氧化潜力和氧化还原稳态来改善氧化锌纳米颗粒诱导的氧化应激
DOI：
10.3389/fpls.2016.00615
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发表时间：
2016
影响因子：
5.6
通讯作者：
Zhou J
中科院分区：
文献类型：
--
作者：
Li M;Ahammed GJ;Li C;Bao X;Yu J;Huang C;Yin H;Zhou J
在过去的几十年里，基于金属的纳米颗粒(MNPs)的使用大幅增加，最终污染了农田，限制了世界范围内的作物生产。此外，由于潜在的健康危害风险，食物链受到MNPs的污染已成为公众关注的问题。油菜素类固醇已被证明在缓解重金属胁迫方面发挥了关键作用，但其在缓解纳米氧化锌(ZnO NPs)诱导的植物毒性方面的作用尚不清楚。在这项研究中，我们研究了24-表油菜素内酯(BR)在减轻纳米氧化锌对番茄幼苗的毒害中的潜在作用。幼苗生长、生物量和根系活力随生长介质(1MS)中纳米氧化锌浓度(10~100 mg/L)的增加而逐渐降低，而锌的积累量逐渐增加。BR(5 NM)浓度的增加可显著改善50 mg/L氧化锌纳米颗粒对细胞生长的抑制作用。番茄根中过氧化氢(H_2O_2)、过氧化氢(H_2O_2)和丙二醛(MDA)的含量测定证实了纳米氧化锌诱导了番茄的氧化胁迫。然而，与单独添加氧化锌纳米粒相比，添加BR和氧化锌纳米粒显著降低了过氧化氢和丙二醛的浓度，表明补充BR显著减轻了氧化应激。此外，BR和氧化锌纳米粒联合处理后，超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶和谷胱甘肽还原酶等关键抗氧化酶的活性比单独处理的提高。BR还可增加还原型谷胱甘肽(GSH)，降低氧化谷胱甘肽(GSSG)，从而通过增加GSH/GSSG比值改善细胞氧化还原动态平衡。铜锌超氧化物歧化酶、CAT1、GSH1和GR1等抗氧化剂基因相对转录丰度的变化与这些抗氧化剂在不同处理下的变化相一致。更重要的是，与单独使用纳米氧化锌相比，BR和纳米氧化锌配施显著降低了番茄幼苗地上部和根部的锌含量。综上所述，本研究首次表明，BR不仅可以提高植物对氧化锌纳米颗粒的耐受性，而且还可以减少番茄幼苗中过量的锌含量。这一发现可能对MNPs污染地区的蔬菜安全生产具有潜在的指导意义。
In the last few decades use of metal-based nanoparticles (MNPs) has been increased significantly that eventually contaminating agricultural land and limiting crop production worldwide. Moreover, contamination of food chain with MNPs has appeared as a matter of public concern due to risk of potential health hazard. Brassinosteroid has been shown to play a critical role in alleviating heavy metal stress; however, its function in relieving zinc oxide nanoparticles (ZnO NPs)-induced phytotoxicity remains unknown. In this study, we investigated the potential role of 24-epibrassinolide (BR) in mitigating ZnO NPs-induced toxicity in tomato seedlings. Seedling growth, biomass production, and root activity gradually decreased, but Zn accumulation increased with increasing ZnO NPs concentration (10–100 mg/L) in growth media (½ MS). The augmentation of BR (5 nM) in media significantly ameliorated 50 mg/L ZnO NPs-induced growth inhibition. Visualization of hydrogen peroxide (H2O2), and quantification of H2O2 and malondialdehyde (MDA) in tomato roots confirmed that ZnO NPs induced an oxidative stress. However, combined treatment with BR and ZnO NPs remarkably reduced concentration of H2O2 and MDA as compared with ZnO NPs only treatment, indicating that BR supplementation substantially reduced oxidative stress. Furthermore, the activities of key antioxidant enzymes such as superoxide dismutase (SOD), catalase, ascorbate peroxidase and glutathione reductase were increased by combined treatment of BR and ZnO NPs compared with ZnO NPs only treatment. BR also increased reduced glutathione (GSH), but decreased oxidized glutathione (GSSG)] and thus improved cellular redox homeostasis by increasing GSH:GSSG ratio. The changes in relative transcript abundance of corresponding antioxidant genes such as Cu/Zn SOD, CAT1, GSH1, and GR1 were in accordance with the changes in those antioxidants under different treatments. More importantly, combined application of BR and ZnO NPs significantly decreased Zn content in both shoot and root of tomato seedlings as compared with ZnO NPs alone. Taken together, this study, for the first time, showed that BR could not only improve plant tolerance to ZnO NPs but also reduce the excess zinc content in tomato seedlings. Such a finding may have potential implication in safe vegetable production in the MNPs-polluted areas.