铀胁迫对酸模叶绿素荧光特性和酶活性的影响

Effect of Uranium Stress on Chlorophyll Fluorescence Characteristics and Enzyme Activity of Rumex Acetosa L.

通过盆栽控制性实验,研究了不同铀浓度处理﹙0、25、50、100、200、400 mg/kg﹚对酸模(Rumex acetosa L.)叶绿素含量、叶绿素荧光特性及抗氧化酶的影响。结果表明:随着土壤铀浓度的增加,叶绿素含量显著下降,最大光化学效率(Fv/Fm)下降但差异不显著,光合性能指数(PIABS)显著下降,K相可变荧光占J相可变荧光比例(Wk)和J相可变荧光(Vj)逐渐升高,单位反应中心吸收的光能(ABS/RC)、单位反应中心捕获的能力(TRo/RC)、单位反应中心捕获的用于电子传递的能量(ETo/RC)和单位反应中心耗散的能量(DIo/RC)均呈先升高后下降的趋势,铀胁迫使酸模整个PSⅡ的结构和功能都受到了伤害,光合作用受到抑制;SOD和POD活性整体呈现先上升后下降的趋势,MDA含量逐渐升高,酸模产生膜脂过氧化,启动了过氧化酶系统。

Controlled pot experiments were conducted to examine the effect of concentration gradient（0,25,50,100,200,400 mg/kg） of uranium on chlorophyll content,chlorophyll fluorescence characteristics and antioxidase of Rumex acetosa.The results demonstrated that both chlorophyll content and performance index（PIABS）decreased significantly with the increase of uranium concentration,and the maximum photochemical efficiency（Fv/Fm）also decreased but slightly. In comparison,the K-phase variable fluorescence/ the J-phase variable fluorescence ratio（Wk）and the J-phase variable fluorescence（Vj）gradually increased with increasing the concentration of uranium. And the energy absorption per active reaction center（ABS/RC）,the capture capability per active reaction center（TRo/RC）,the capture energy was used for electron transfer per active reaction center（ETo/RC） and the non-photochemical energy dissipation per active reaction center（DIo/RC） all increased at the beginning and then decreased as the concentration of uranium increased. The results above indicated the photosynthesis was inhibited,as a result of the damage of the structure and function of Rumex acetosa＇s PS Ⅱ under the stress of uranium. The SOD and POD activities increased at first and then decreased,and the content of MDA increased gradually with an increase of uranium concentration. Consequently,the membrane lipids of Rumex acetosa peroxided,and the Rumex acetosa started antioxidant enzyme system.