重金属复合胁迫下碱蓬萌发生长及富集特征

Seed germination, bud growth and heavy-metal accumulation of Suaeda salsa

摘要:

为探究重金属复合胁迫对金川镍铜矿区广布植物碱蓬Suaeda salsa (L.) Pall.的影响，根据当地环境条件及预实验结果设置胁迫梯度，测定分析重金属胁迫下碱蓬种子萌发和芽期生理指标，并从野外站台取样研究碱蓬重金属富集能力。结果表明：无论是单一胁迫还是低浓度复合胁迫 (Cu20和Ni20复合)，发芽期碱蓬的生长均呈现“低促高抑”的趋势，即低浓度 (≤40 mg/L) 时促进碱蓬生长，高浓度 (≥80 mg/L) 时抑制碱蓬生长；高浓度复合胁迫 (Cu320和Ni320复合) 下均抑制碱蓬的生长。MDA (丙二醛) 的含量随胁迫浓度的增加而增加；胁迫组可溶性蛋白和游离脯氨酸含量整体上高于对照组；单一胁迫下POD (过氧化物酶) 活性随胁迫浓度增加而增加；复合胁迫下低浓度提高POD活性，高浓度抑制POD活性；碱蓬叶片的平均转移系数 (TF) 大于茎部，且平均转移系数大于1.00；碱蓬叶片的富集系数(BCF)大于根部大于茎部。碱蓬对Cu和Ni均具有很高的耐受性，但对于Cu的耐性强于Ni；低浓度时Cu、Ni复合胁迫对碱蓬生长的促进作用强于Cu、Ni单一胁迫，高浓度时则相反；碱蓬具有较高的重金属富集和转移能力；在当前矿区土壤环境背景下，碱蓬可以作为矿区生态恢复和重金属污染修复的备选植物。

Abstract:

Nickel and copper, as high toxic heavy metals (HMs), are the most serious contaminants in Jinchuan mining area, China. In this paper, the influence of combined HMs stress on the growth of widespread plant-S. salsa has been studied. The stress gradient of combined Ni-Cu was set based on the local environment and pre-experiment. Seed germination, growth, physiological characteristics of S. salsa were investigated by the control test, and its heavy metal bioaccumulation capacity was investigated by samples collected from field platform. The growth of S. salsa was promoted at lower concentration (≤40 mg/L) and inhibited at higher concentration (≥80 mg/L) under the single HMs stress and combined HMs stress (Cu20/Ni20). The malondialdehyde (MDA) content was increased with increasing concentration, and the soluble protein and free proline content in stress group were higher than that of in control group. Under single HMs stress, the peroxidase (POD) activity increased with increasing concentration; while under combined HMs stress, the POD activity increased initially and then reduced. Cu320 and Ni320 combined HMs stress inhibited the growth of S. salsa at all concentrations. The average translocation factors (TF) of S. salsa were greater than 1.00, and higher in leaves compared to stems. The results of bio-concentration factors (BCF) of S. salsa show that BCF of leaves were larger than that of roots and stems. At lower concentration, the combined HMs stress promoted the growth of S. salsa in comparison to single HMs stress, however, opposite results were obtained at higher concentration. Overall, S. salsa showed high tolerance to Cu and Ni and stronger capabilities of HMs uptake and translocation, and therefore, it can be used as an alternative plant for the bioremediation of heavy metal pollution in mining area.