Mn污染对木荷叶片抗氧化酶系统的影响

Effects of Manganese Contamination on Activities of Antioxidant Enzyme Systems in Leaves of Schima superba

采用土培方法,研究了广西桂林市未受污染土壤(对照)及贺州市某锰矿的未开采区、探矿区、恢复区、采矿区土壤和尾砂对Mn富集植物木荷(Schima superba)生长、Mn吸收,叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)活性,抗坏血酸(AsA)、谷胱甘肽(GSH)、植物络合素(PCs)、巯基(-SH)、丙二醛(MDA)、过氧化氢(H2O2)含量,以及超氧阴离子自由基(O-2·)产生速率的影响。结果表明,随着土壤Mn含量的增加,木荷根、茎、叶中Mn含量均显著增加(P<0.05),株高及株重呈先上升后下降的趋势,表明一定程度的Mn能促进木荷的生长。土壤Mn含量的增加,使得叶片中O-2·的产生速率及H2O2的含量呈现不同程度的变化,采矿区土壤栽培的木荷叶片中O-2·的产生速率显著高于对照(P<0.05),开采区土壤和尾砂栽培的木荷叶片中H2O2含量比对照分别提高了65.7%、96.3%,矿区土壤栽培的木荷叶片中MDA的含量均显著高于对照(P<0.05),表明叶片受到一定的胁迫。木荷叶片中抗氧化酶活性与非酶物质变化不尽相同,SOD、POD酶活性、AsA、GSH含量均随着土壤Mn浓度的增加而增加,CAT、APX酶的活性呈先升后降趋势,其中尾砂栽培的木荷POD酶的活性最高,比对照提高了1.62倍,采矿区土壤和尾砂栽培的木荷GSH的含量显著高于对照(P<0.05),分别比对照提高了1.66和1.79倍。

Manganese（Mn）is essential for plant growth,but excess Mn may impact antioxidant enzyme systems in plant. A soil culture experiment was performed to explore the effects of Mn contamination on various enzymatic antioxidants and non-enzymatic antioxidants in the leaves of Schima superba. Soil samples,collected from unmining section（WK）,prospecting area（T）,restored area（H）,mining（K）and tailings（W）in a manganese mine of Hezhou,were used as Mn-polluted soils,and an unpolluted soil from Guilin,Guangxi was used as contro（lCK）. After 145-d of culture,leaves of S. superba were sampled and analyzed for the activities of superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）,and ascorbate peroxidase（APX）and the contents of ascorbic acid（AsA）,glutathione（GSH）,phytochelatins（PCs）,total acid soluble SH,malondialdehyde（MDA）,hydrogen peroxide（H2O2）,and the produce rate of superoxide anion（O2·^-. Concentrations of Mn in roots,stems,and leaves increased with soil Mn concentrations. Compared to the control,plant biomass increased in WK and T samples,whereas decreased in the other soils,indicating stimulation of S. superba growth by Mn at low concentrations. The rate of O2·^-roduction in the leaves was significantly higher in H than in contro（P〈0.05）. The contents of H2O2in leaves were increased by 65.7% and96.3% for K and W,respectively. The leaf MDA was significantly（P〈0.05）higher in mineral soils than in control,showing that the leaves were damaged by Mn pollution. The activities or contents of SOD,POD,AsA and GSH increased in order of CKWKTHKW,in consistency with soil Mn concentrations. The POD enzyme activity in leaves in W soil was 2.62 times as much as that of control. Both CAT and APX enzymatic activities increased in WK and T,but decreased in the others,as compared with the control. The contents of GSH in leaves in K and W were about 1.66 and 1.79 times higher than those of the control.