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浙江大学学报（农业与生命科学版）
Journal of Zhejiang University (Agriculture and Life Sciences)  2016, Vol. 42 Issue (1): 89-98    DOI: 10.3785/j.issn.1008-9209.2015.07.011
Resource & environmental sciences     
Effects of soil Fe2+and Cd2+ on activities of antioxidant enzymes and Cd accumulation in rice plants
YE Xinyi, ZHAO Xing, WANG Xiaopeng, ZHONG Yiming, YANG Jingping
(College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China)
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Abstract  Divalent heavy metal cation cadmium (Cd2+) causes phytotoxicity in plants. The high bioaccumulation index in plants and soil will also threat the human health through food chain. It has been shown that Cd will inhibit germination of seeds and exert a wide range of adverse effects on growth and metabolism of plants. It was reported that high concentration of Fe2+ in paddy soil could exert some impacts on plant growth and Cd2+ accumulation. Cadmium and ferrous with high concentration in soil, are known to cause oxidative damage to plants either directly or indirectly by triggering an increased level of production of reactive oxygen species (ROS). Plants have antioxidative enzymes, such as superoxide dismutase (SOD), catalase and peroxidase (POD), which can scavenge ROS to avoid oxidative damage. Malondialdehyde (MDA) level is used as an index of lipid peroxidation under stressful conditions in plants. Therefore activity of antioxidative enzymes (SOD and POD) and MDA level can be used to monitor the oxidative stress of plants. In anaerobic waterlogged environment, rice can form iron plaque around root surface and screen metals by adsorption and co-precipitation. Thus, the availability and balance of Fe/Cd in the rhizosphere of rice will be influenced. Many researchers investigated the impacts of ferrous and cadmium respectively on rice growth, while few efforts were made in interaction of these two metal ions, which exist in production conditions. In order to investigate mechanisms of Fe and Cd stress on rice in real production condition, the pot experiment with 4 soil Fe2+ levels (577, 677, 777 and 977  mg/kg) and 2 soil Cd2+ concentrations (0.413 and 5.413 mg/kg) was conducted. The rice cultivar used in the experiment was Hang43. Shoots of rice collected at booting stage were ground with liquid nitrogen and were homogenized in phosphate buffer (pH 7.8). The extracted supernatant was used to assay SOD activity, POD activity and MDA level, by NBT method, guaiacol colorimetric method and the thiobarbituric acid method, respectively. Fe and Cd concentrations in shoots and roots were determined by flame atomic absorption spectrophotometer (FAAS) after digestion procedures. Fe and Cd contents in iron plaque on the roots were extracted using dithionite-citrate-bicarbonate (DCB) method, and were measured by AAS. The experimental results showed that ferrous and cadmium in soil had interaction on the activities of lipid peroxidation, antioxidative enzymes and uptakes of these two metals. Cd2+ remarkably decreased MDA levels by about 31.1%, meanwhile depressed activities of superoxide dismutase (SOD) and peroxidase (POD) enzyme. Whereas, those adverse effects were mediated by increasing Fe2+ concentration in soil (especially at 977 mg/kg Fe2+). Variations of SOD activity and POD activity had similar trend in all the treatments, though POD activity was more stabilized, indicating SOD undertakes more protection responsibility under experimental conditions. Fe contents in iron plaque maintained 1-2 g/kg under all treatments, while Cd concentration in iron plaque declined quickly with the increase of soil ferrous level. Ferrous in soil stimulated the uptakes of Cd at a certain range but a relatively higher ferrous concentration in soil decreased the Cd contents in roots and shoots. It can be concluded that iron plaque helps to screen Cd2+ in the rhizosphere and inhibits the uptake of Cd2+ in rice. Fe2+in soil can alleviate the stress of Cd2+ by restraining the accumulation of Cd2+.

Published: 20 January 2016
CLC:  X 53  
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YE Xinyi
ZHAO Xing
WANG Xiaopeng
ZHONG Yiming
YANG Jingping
Cite this article:

YE Xinyi, ZHAO Xing, WANG Xiaopeng, ZHONG Yiming, YANG Jingping. Effects of soil Fe2+and Cd2+ on activities of antioxidant enzymes and Cd accumulation in rice plants. Journal of Zhejiang University (Agriculture and Life Sciences), 2016, 42(1): 89-98.

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http://www.zjujournals.com/agr/10.3785/j.issn.1008-9209.2015.07.011     OR     http://www.zjujournals.com/agr/Y2016/V42/I1/89


土壤亚铁、镉对水稻2种抗氧化酶和植株富集镉量的影响

我国南方潴育及潜育型水稻土中积累有大量亚铁,有研究表明土壤亚铁会影响镉在植株中的富集及镉对植株的氧化性胁迫。试验设置4个土壤Fe2+水平(外源加入亚铁分别为0 mg/kg、100 mg/kg、200 mg/kg和400 mg/kg)和2个Cd2+水平(外源加入镉分别为0 mg/kg和5 mg/kg),研究不同亚铁和镉的共同作用对孕穗期水稻叶片脂质过氧化、抗氧化酶活性以及对根膜和植株中重金属累积量的影响。在无外源亚铁添加的条件下,镉使叶片中脂质过氧化的监测指标丙二醛(malondialdehyde,MDA)含量下降了31.1%,同时抑制了超氧化物歧化酶(superoxide dismutase,SOD)和过氧化物酶(peroxidase,POD)活性。随着土壤亚铁量的增加,特别是在外源添加亚铁400 mg/kg时,镉对水稻植株产生的上述影响得到了缓解。随着土壤亚铁量的升高,水稻的根膜、根和叶片对重金属镉的富集呈下降的趋势,且试验表明水稻根及叶片对镉的积累与根际膜中含镉量呈显著正相关。研究表明土壤中亚铁量的增加会降低水稻中镉的积累。
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