Cs对菠菜叶片光合作用影响的研究

Study on the Effects of Cesium on Photosynthesis of Spinach

为了揭示Cs对植物光合作用的影响机理,本文采用不同浓度的Cs Cl(0、1、5、10、20 mmol·L-1)和石英砂培处理菠菜幼苗15 d,分析测定了Cs在菠菜中的积累分布以及Cs对菠菜叶片叶绿素含量、光合气体交换参数、叶绿素荧光参数、类囊体膜电子传递速率、类囊体膜吸收光谱和77k低温荧光光谱的影响。结果表明:Cs处理显著降低菠菜叶片的叶绿素含量;随着Cs处理浓度的增加,尤其在处理浓度大于10 mmol·L-1时,叶片净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)以及蒸腾速率(Tr)显著下降;叶片叶绿素荧光参数分析表明,Cs处理浓度大于10 mmol·L-1时,光系统II(PSII)反应中心遭到破坏;类囊体膜电子传递活性分析表明高浓度Cs处理抑制PSII放氧侧的电子传递活性;类囊体膜室温吸收光谱和77K低温荧光光谱分析表明高浓度Cs会破坏类囊体膜的结构,导致叶绿素的结合状态受损,从而使类囊体膜光能的吸收、传递和分配受到抑制,并且会导致类囊体膜上PSII和PSI的色素蛋白发生不同程度的降解。本研究可为Cs污染的植物修复提供一定理论依据。

In order to contribute to the understanding of the photosynthesis characteristics changes induced by cesium, five-leaf stage spinach seedlings raised in quartz salad and Hoagland solution culture system, were provided with a nutrient solution with the supplement of different concentrations Cs （0, 1, 5, 10, 20 mmol·L^-1CsCl） for 15 days,and then chlorophyll content, photosynthetic gas exchange parameters, chlorophyll fluorescence parameters, electron transfer activity, absorbance spectra and 77k low fluorescence spectra of thylakoid membranes were investigated. The results showed that： The chlorophyll content decreased significantly compared with the control under the different Cs^＋ concentrations; under the low Cs^＋ concentrations, net photosynthesis （ Pn）, stomatal conductance （ Gs）, intercellular CO2 concentration （Ci）, transpiration rate （Tr） changed insignificantly and along with elevated levels of applied Cs^＋ from 10 mmol·L^-1 as well as the duration of treatment, all the parameters decreased significantly. The analysis of chlorophyll fluorescence parameters showed that the activity of photosystem II （PSII） reaction centers were damaged under high Csconcentrations. The analysis of the electron transfer activity of thylakoid membranes showed the inhibition of electron transfer activity of PSII by high Csconcentrations; The absorbance spectra and 77k low fluorescence spectra revealed that Cs could damage the structure and function of thylakoid membranes, and cause the inhibition of the light energy absorption, transmission and distribution, and even lead to the degradation of pigment protein complexes of thylakoid membranes.