外源钙和亚精胺对镉胁迫下苎麻生理响应的影响研究

发布时间：2018-06-03 23:05

本文选题：苎麻 + 镉　；参考：《湖南大学》2015年硕士论文

【摘要】：本研究采用素有“中国草”之称的中国特有的以纺织为主要用途的作物——苎麻作为实验选材,重金属镉(Cd)为目标污染物,研究外源钙(Ca)和亚精胺(Spd)对镉胁迫下苎麻幼苗生长、光合作用、抗氧化作用及Cd吸收转运的影响,探索外源物质对苎麻修复镉污染影响的作用机理。实验结果表明:5 mg/L Cd处理下,苎麻根茎叶中Cd浓度分别为309.67 mg/kg、117.08 mg/kg、87.72 mg/kg,这表明苎麻对Cd有一定程度的富集能力,可用于重金属Cd污染的植物修复。但Cd处理下苎麻生物量、可溶性蛋白、叶绿素含量等都显著降低,而脯氨酸、过氧化氢、丙二醛含量大幅增加,抗氧化物酶(SOD、CAT、POD、APX)活性及抗氧化物质(GSH、维生素E)水平等均发生变化,说明Cd胁迫通过影响植物生长发育、光合作用、生理代谢、氧化程度等对苎麻产生了毒害作用。外源Ca对苎麻重金属Cd吸收及转运的影响很大:所有浓度的Ca处理都增加了Cd从苎麻根部到地上部分的转运能力。特别是低浓度Ca(1 mmol/L)处理,其在提高Cd的转运系数(TF1)的同时还大幅增加了苎麻茎和叶对重金属Cd的吸收,使得苎麻地上部分积累的重金属Cd浓度超过100 mg/kg DW。不同浓度外源Ca对Cd胁迫下植物生理指标的影响存在差异:中浓度Ca(5 mmol/L)处理增加了苎麻生物量、可溶性蛋白浓度、植物体内叶绿素含量,降低了重金属Cd的积累和脯氨酸水平,该浓度Ca处理通过调节上述生理指标起到了缓解Cd毒害的作用;而低浓度Ca(1 mmol/L)处理则通过增加重金属Cd的积累及脯氨酸水平,降低苎麻地上部分及地下部分生物量和可溶性蛋白质含量加剧了Cd的毒害作用;高浓度Ca(10 mmol/L)处理则通过降低可溶性蛋白的含量,表现出一定程度的毒害作用。Spd与Ca的联用效果因Ca浓度不同产生不同的结果:与1 mmol/L Ca+Cd处理相比,Spd可显著增加苎麻根茎叶的生物量。在植物抗氧化胁迫方面,Spd的添加可通过降低MDA及H2O2浓度,调节抗氧化物酶SOD、CAT、POD、AP X等的活性,提高抗氧化物质GSH、维生素E的水平等缓解由1 mmol/L Ca+Cd处理对苎麻造成的氧化胁迫作用。但5 mmol/L Ca+Cd处理下Spd的缓解作用则不明显。综上所述,Cd胁迫严重影响了苎麻的生长及生理代谢,5 mmol/L Ca处理可缓解Cd的毒害作用;外源1 mmol/L Ca处理可增加苎麻对Cd的吸收及转运但会加剧Cd的毒害作用;Spd与1 mmol/L Ca联用,则可在增加苎麻对重金属吸收及转运水平的基础上缓解Cd对植物产生的毒害作用。
[Abstract]:In this study, the growth of Ramie seedlings under cadmium stress was studied by using Chinese unique crop-Ramie, which is known as "Chinese grass" and heavy metal cadmium and cadmium (CD) as the target pollutant, to study the effects of exogenous Ca) and spermidine (Spd) on the growth of Ramie seedlings under cadmium stress. The effects of photosynthesis, antioxidation and CD absorption and transport on the effects of exogenous substances on the remediation of cadmium pollution in Ramie were explored. The results showed that the CD concentrations in Ramie roots and leaves were 309.67 mg / kg, 117.08 mg / kg, 87.72 mg / kg, respectively, which indicated that Ramie had a certain degree of CD enrichment ability and could be used for the phytoremediation of heavy metal CD pollution. However, the biomass, soluble protein and chlorophyll content of Ramie decreased significantly under CD treatment, while the contents of proline, hydrogen peroxide and malondialdehyde increased significantly, and the activities of antioxidant enzyme SODCAT PODX (APX) and the level of antioxidant substances (GSH, vitamin E) were all changed. CD stress had toxic effects on Ramie by affecting plant growth and development, photosynthesis, physiological metabolism and degree of oxidation. The effect of exogenous Ca on the absorption and transport of heavy metal CD in Ramie was very great: all the Ca treatments increased the transport ability of CD from Ramie roots to aboveground parts. Especially, the low concentration of Ca(1 mmol / L increased CD transport coefficient (TF1) and significantly increased the uptake of heavy metal CD in Ramie stems and leaves, which led to the accumulation of CD in Ramie aerial parts over 100 mg/kg DW. The effects of exogenous Ca at different concentrations on plant physiological indexes under CD stress were different: middle concentration of Ca(5 mmol / L increased Ramie biomass, soluble protein concentration, chlorophyll content, CD accumulation and proline level. This concentration of Ca could alleviate CD toxicity by regulating the physiological indexes mentioned above, while the low concentration of Ca(1 mmol / L could increase the accumulation of heavy metal CD and proline level. The reduction of biomass and soluble protein content in aboveground and underground parts of Ramie increased the toxicity of CD, while the high concentration of Ca(10 mmol / L decreased the content of soluble protein. Compared with 1 mmol/L Ca CD treatment, SPD could significantly increase the biomass of Ramie rhizomes and leaves. In the aspect of plant antioxidant stress, the addition of SPD could reduce the concentration of MDA and H2O2, regulate the activity of antioxidant enzyme SODCATCATPODX, and increase the level of antioxidants GSH and vitamin E to alleviate the oxidative stress caused by 1 mmol/L Ca CD treatment on Ramie. However, the response of Spd to 5 mmol/L Ca CD treatment was not obvious. In conclusion, CD stress seriously affected the growth and physiological metabolism of Ramie treated with 5 mmol/L Ca, and exogenous 1 mmol/L Ca treatment could increase the CD uptake and transport of Ramie, but increase the toxic effect of CD in combination of SPD and 1 mmol/L Ca. On the basis of increasing the heavy metal uptake and transport level of Ramie, the toxic effect of CD on plants was alleviated.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X503.231

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