Mn对超富集植物短毛蓼（Polygonum pubescens Blume）抗氧化机理的影响

采用水培的方法,研究了不同浓度Mn（0、0.5、1、2、4、8mmol·L-1）对新发现的Mn超富集植物短毛蓼（Polygonum pubescens Blume）生长、Mn吸收及Mn对其抗氧化酶和非酶系统的影响。结果表明,锰处理显著增加了（P〈0.05）短毛蓼根、茎、叶中Mn的含量,锰处理还引起了短毛蓼叶片中过氧化氢（H2O2）和丙二醛（MDA）的累积。当Mn处理浓度大于1mmol·L-1时,显著降低了短毛蓼的株高、株重（P〈0.05）;当Mn处理浓度为8mmol·L-1时,短毛蓼叶片中叶绿素a、叶绿素b、叶绿素a＋b含量最低,与对照差异显著（P〈0.05）。Mn处理显著提高了短毛蓼叶片中超氧物歧化酶（SOD）活性（P〈0.05）,而过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）的活性呈先升后降趋势,表明Mn处理打破了短毛蓼活性氧物质的正常代谢,并启动了抗氧化酶系统。8mmol·L-1的Mn处理,显著提高了短毛蓼叶片中巯基（-SH）、还原型谷胱甘肽（GSH）的含量（P〈0.05）,比对照分别提高了10.6%和20%,表明-SH、GSH在短毛蓼缓解Mn毒害的过程中起着重要作用。

Effects of Manganese on Enzymatic and Non-enzymatic Antioxidative Defenses of the Hyperaccumulator Polygonum pubescens Blume

The effects of manganese（Mn） on various enzymatic antioxidants and non-enzymatic antioxidants in Polygonum pubescens Blume were studied.Polygonum pubescens Blume a newly identified Mn hyperaccumulator,was grown in hydroponic culture added with various Mn concentrations（0,0.5,1,2,4,8 mmol·L-1） for 8 days.Plant leaves were analyzed for contents of glutathione（GSH）,phytochelatins（PCs） and total acid soluble SH,chlorophyll,malondialdehyde（MDA） and activities of superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）and ascorbate peroxidase（APX）.Research findings showed that plant height and biomass had significantly（P0.05） decreased with Mn concentrations beyond 1 mmol·L-1;while chlorophyll contents did not change significantly（P0.05） until Mn concentration reached 8 mmol·L-1.The content of Mn in the tissue of leaves,roots and stems were increased with the increment of Mn treatment concentrations,and the Mn concentration in the leaves were higher than that in the stems and roots under all treatments.Mn pollution induced antioxidant stress which expressed as the accumulation of H2O2,and MDA in plant tissues.Mn treatment raised superoxide dismutase（SOD） activity,however,activities of peroxidase（POD）,catalase（CAT） and ascorbate peroxidase（APX） in leaves firstly rose and then dropped with Mn exposure,showing that the enzymatic system was interrupted.The contents of GSH,and-SH rose with the increment of Mn treatment concentrations.Compared with the control,the contents of GSH and-SH in leaves increased significant（P0.05） under high Mn exposure（8 mmol·L-1）,indicating that the non-enzymatic antioxidants（-SH,GSH） played an important role in the detoxification of Mn in this plant.