硅对锰-铅复合胁迫下水稻幼苗叶片细胞壁多糖组分中锰和铅含量的影响

Effects of silicon on manganese and lead contents in cell wall polysaccharide components of rice seedling leaves under manganese⁃lead combined stress

【目的】探究不同浓度SiO_(2)对锰-铅(Mn-Pb)复合胁迫下水稻幼苗叶片细胞壁多糖组分中Mn和Pb含量的影响,为利用农艺措施治理矿区农田重金属复合污染提供理论依据。【方法】在模拟矿区重金属污染前提下,先用水培法将水稻种子培养至5叶1心期,然后用2 mmol/L Mn^(2+)+2 mmol/L Pb2+溶液复合胁迫水稻幼苗。设6个不同的SiO_(2)处理浓度:0(对照,CK)、70、90、110、130和150 mg/L。处理后提取水稻幼苗叶片细胞壁多糖组分,测定和分析其中Mn和Pb含量。【结果】施加SiO_(2)增加细胞壁多糖组分(果胶质、半纤维素和纤维素)中Mn和Pb含量。与CK相比,当SiO_(2)浓度为70~110 mg/L时,细胞壁果胶质中Mn和Pb含量较高;SiO_(2)处理下果胶质中Pb含量大于Mn含量,当SiO_(2)浓度小于90 mg/L时,水稻幼苗叶片细胞壁中Pb含量小于Mn含量。SiO_(2)浓度为110 mg/L时,在半纤维素和纤维素中Mn和Pb含量均较高;水稻幼苗叶片细胞壁半纤维素中Pb含量大于Mn含量,SiO_(2)浓度小于90 mg/L时,纤维素中Pb含量为负值。未施加SiO_(2)时,Mn和Pb的主要结合位点分别为纤维素和果胶质,施加SiO_(2)使Pb的主要结合位点转移为半纤维素。【结论】SiO_(2)能增加重金属Mn和Pb在细胞壁多糖组分中的含量。Mn-Pb复合胁迫下,SiO_(2)浓度为110 mg/L时,Mn和Pb的含量在细胞壁、果胶质、半纤维素和纤维素中均较多。

【Objective】The study aimed to explore the effects of different concentrations of SiO_(2) on manganese(Mn)and lead(Pb)contents in cell wall polysaccharide components of rice seedling leaves under Mn⁃Pb composite stress,and to provide theoretical basis for the use of ag⁃ronomic measures to treat heavy metal composite pollution in mining fields.【Method】Under the premise of simulating heavy metal pollution in the mining area,rice seeds were first cultivated to 5 leaves and 1 heart stage by hydroponics,and then rice seedlings were subjected to com⁃pound stress with 2 mmol/L Mn^(2+)+2 mmol/L Pb2+solution.Six SiO_(2) treatment concentrations were set:0(control group,CK),70,90,110,130,and 150 mg/L.After treatment,cell wall polysaccharide components of rice seedling leaves were extracted,and the contents of Mn and Pb were determined and analyzed.【Result】The content of Mn and Pb in the polysaccharide components of cell wall(pectin,hemicellu⁃lose and cellulose)was increased by SiO_(2) application.Compared with CK,the contents of Mn and Pb in cell wall pectin were higher when the concentration of SiO_(2) was 70-110 mg/L.Under the treatment of SiO_(2),the content of Pb was greater than Mn content in pectin,and when the concentration of SiO_(2) was less than 90 mg/L,the content of Pb was less than Mn in the leaf cell wall of rice seedlings.When the concentration of SiO_(2) was 110 mg/L,the content of Mn and Pb was relatively high in hemicellulose and cellulose.The content of Pb in the cell wall hemi⁃cellulose of rice seedling leaves was higher than the Mn content,and content of Pb in cellulose was negative when the concentration of SiO_(2) was less than 90 mg/L.When SiO_(2) was not applied(CK),the main binding sites of Mn and Pb were cellulose and pectin respectively,and the main binding sites of Pb were transferred to hemicellulose when SiO_(2) was applied.【Conclusion】SiO_(2) can increase the content of heavy metals Mn and Pb in the cell wall polysaccharide components.Under Mn⁃Pb combined stress,when SiO_(2) concentration is 110 mg/L,Mn and Pb contents are more in cell wall,pectin,hemicellulose and cellulose.