硒对茶树镉毒害的缓解作用研究

The alleviating effects of selenium on cadmium-induced toxicity in tea leaves

【目的】通过溶液培养试验,探讨硒(Se)对镉(Cd)胁迫下茶树生长和生理特性的影响,为保障茶叶饮用安全和综合开发利用提供参考。【方法】以种植于陕西汉中地区的‘龙井43'茶树为试验材料,采用营养液培养方法,分别进行镉和硒处理试验,包括7个处理,分别为Cd 10 mg/L、Se 0.5 mg/L、Se 1.5 mg/L、Se 3.0 mg/L、Se 0.5 mg/L+Cd 10.0 mg/L、Se 1.5 mg/L+Cd 10.0 mg/L、Se 3.0 mg/L+Cd 10.0 mg/L。测定了不同质量浓度硒处理缓解茶树叶片镉毒害的生理响应,以及茶树叶生物量,茶树叶硒和镉的含量。【结果】与未施加镉和硒的对照相比,单一施镉处理使得茶树叶片的光合色素含量、过氧化氢酶(CAT)、抗坏血酸过氧化物酸(APX)、谷胱甘肽过氧化物酶(GPX)活性,以及生物量和可溶性糖、可溶性蛋白含量受到明显抑制,而丙二醛(MDA)和过氧化氢(H2O2)含量、渗透调节物质脯胺酸含量明显增加。单一施硒处理条件下,与单一施镉处理对比,上述指标均不同程度得到显著改善,其中1.5mg/L硒处理下茶树叶片的各项指标改善程度最高。与单一施镉处理相比,在镉和硒的复合处理下,随着硒含量提高,上述各项指标均不同程度得到改善,以Se 1.5mg/L+Cd 10.0 mg/L复合处理下的各项指标改善程度最高。硒的施加有助于缓解茶树叶片镉的积累。【结论】施加适量的硒在一定程度上可以增加茶树叶片镉诱导产生的抗氧化酶CAT、APX和GPX活性,降低质膜过氧化产物MDA和H2O2含量积累,缓解镉对茶树叶片的毒害,并降低对镉的积累。

【Objective】We examined the effects of selenium(Se)on the growth and physiological characteristics of tea plants subjected to cadmium(Cd)based on a culture solution experiment,the findings of which will provide a theoretical basis for ensuring the safety of tea drinking and the comprehensive development and utilization of tea.【Method】As experimental material,we used‘Longjing 43'tea trees leaves planted in the Hanzhong area of Shaanxi Province,China,which were exposed to the following seven combinations of Cd and Se in 1/2 Hoagland solution:10 mg/L Cd,0.5 mg/L Se,1.5 mg/L Se,3.0 mg/L Se,0.5 mg/L Se+10.0 mg/L Cd,1.5 mg/L Se+10.0 mg/L Cd,and 3.0 mg/L Se+10.0 mg/L Cd.Following treatment,we determined the physiological responses associated with the alleviation of Cd toxicity in tea leaves treated with different concentrations of Se(0.5-3.0 mg/L),and measured the biomass of tea leaves,and the concentrations of Se and Cd in these leaves.【Result】Compared with the control treatment without either Cd or Se addition,the treatment with Cd alone promoted a significant decrease in the concentration of photosynthetic pigments,antioxidant enzymes[catalase(CAT),ascorbate peroxidase(APX)and glutathione peroxidase(GPX)],biomass,and the concentrations of soluble sugars and soluble protein in tea leaves,whereas the contents of malondialdehyde(MDA),hydrogen peroxide(H2O2),and proline were significantly increased.In samples treated with Se alone,the above indices(e.g.biomass,and the concentrations of soluble sugars,soluble protein,and photosynthetic pigments,antioxidant enzymes activities in tea leaves)were significantly improved to differing extents compared with the Cd only treatment,particularly in response to treatment with 1.5 mg/L.In the combined Cd and Se treatments,we noted that the indices were improved to varying degrees in response to increases in Se concentration compared with the Cd only treatment,with the most pronounced improvement being obtained in response to the combined treatment of 1.5 mg/L Se+10.0 mg/L Cd.The application of selenium reduced the accumulation of cadmium in tea leaves.【Conclusion】To differing extents,the addition of an appropriate amount of Se can increase the activities of CAT,APX and GPX induced by Cd in tea leaves,reduce the accumulation of MDA and H2O2,and alleviate Cd toxicity.