镉胁迫对秋华柳植物螯合肽含量的影响

Effect of cadmium stress on the content of phytochelatins in Salix variegata

以秋华柳为试验对象,采用水培法,设置0 mg/L Cd^(2+)(CK)、2 mg/L Cd^(2+)(T_1)、10 mg/L Cd^(2+)(T_2)、20 mg/L Cd^(2+)(T_3)、50 mg/L Cd^(2+)(T4_)5种镉处理水平,通过对不同时间、不同质量浓度Cd^(2+)处理下秋华柳叶片和根系中镉含量和各巯基肽含量的测定,研究Cd胁迫下秋华柳植物体内巯基肽的螯合解毒机制。结果表明:1)在Cd胁迫下,叶片诱导生成4种植物螯合肽(PC2、PC3、PC4和PC5),根系诱导生成2种植物螯合肽(PC2和PC3)。2)各处理组秋华柳叶片和根系中的巯基肽总量明显高于对照,且随着处理时间的延长和Cd胁迫程度的增加而升高。秋华柳叶片和根系中的谷胱甘肽含量均高于对照,且在一定质量浓度的Cd^(2+)处理水平下差异有统计学意义;在秋华柳叶片中,各处理组的PCs含量均显著高于对照,且随着Cd胁迫程度的增加而升高;在秋华柳根系中,各处理组的PC2含量均显著高于对照,T4处理组的PC3含量显著高于对照。秋华柳叶片和根系中各巯基肽含量与其对应的Cd积累量之间均呈显著正相关。3)各处理组秋华柳叶片和根系中的PC2为含量最高的巯基肽,且根系中PC2占的比例更大。综上表明:在Cd胁迫下,秋华柳叶片和根系中的巯基肽含量随Cd积累量的增加而增加,从而增强其对Cd的螯合作用,提高对Cd的耐受和解毒能力;且秋华柳细胞内的PC2对Cd的螯合作用最强,尤其是在根部。

With rapid development of industrialization and urbanization in China,large amounts of heavy metals have been directly or indirectly released into the soil environment through solid wastes,waste air,and waste water from industrial activities over the recent decades.In particular,cadmium(Cd)is one of the most toxic pollutants causing environmental problems.With excellent water solubility,Cd can be absorbed by plants easily and transferred to human body,eventually threatening the health of human beings.Lots of herb plants have tolerance for Cd and can accumulate to eliminate the Cd pollution in soils.However,with relative low biomass,the accumulation capacity of herb plants is limited.Little is known about the phytoremediation application of woody plants,which have large biomass and fast growth rate.Salix variegata has strong bioaccumulation on Cd and exceptionally high tolerance to Cd stress,especially planted along the sloping banks,thus it has the potential for phytoremediation of Cd polluted environments.However,the mechanism of tolerance and detoxification for Cd still needs further study.Metal binding ligands are effective for detoxification of heavy metals,mainly phytochelatins(PCs)and metallothioneins(MTs).