光系统Ⅱ实际光化学量子效率对光的响应模型的比较  

Comparison on light-response models of actual photochemical efficiency in photosystem Ⅱ

作　　者：叶子飘[1] 胡文海[2] 闫小红[2,3] 

机构地区：[1]井冈山大学数理学院,江西吉安343009 [2]井冈山大学生命科学学院,江西吉安343009 [3]南京林业大学森林资源与环境学院,南京210037

出　　处：《植物生态学报》2016年第11期1208-1217,共10页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31560069);江西省自然科学基金(20142BAB20402)

摘　　要：为了比较光系统Ⅱ实际光化学量子效率(FPSⅡ)对光的响应机理模型(简称机理模型)、负指数模型和指数模型的优缺点,用LI-6400-40B光合作用测定仪控制CO2浓度和温度,测量了剑叶金鸡菊(Coreopsis lanceolata)、黄荆(Vitex negundo)和大狼杷草(Bidens frondosa)的电子传递速率(ETR)对光的响应曲线(ETR-I)和FPSⅡ对光的响应曲线(FPSⅡ-I),然后用这3个模型分别拟合了这些数据。拟合结果表明:3个模型都可以较好地拟合这3种植物的ETR-I的响应数据和FPSⅡ-I的响应数据,但由指数模型拟合ETR-I和FPSⅡ-I的响应数据得到相应的饱和光强(PARsat)和光系统Ⅱ最大光能利用效率(Fv/Fm)之间存在显著差异,且估算的饱和光强远低于实测值。由机理模型可知,FPSⅡ不仅与光强的函数有关,还与植物的内禀特性有关,即与天线色素分子的本征光能吸收截面、激子的传递效率、能级的简并度、光化学反应常数、热耗散常数和处于最低激发态的平均寿命等参数有关。此外,由机理模型还可知,FPSⅡ随光强的增加而下降的原因是捕光色素分子的有效光能吸收截面随光强增加而降低。Aims The objective of this study was to compare the merits and demerits of three models（i.e., a mechanistic model, a negative exponential model and an exponential model） to simulate the light-response curves of actual photochemical efficiency（（37）PSⅡ-I）. Moreover, it was to reveal the mechanism that（37）PSⅡ decreased with light intensity increasing. Methods The electron transport rate（ETR） and the（37）PSⅡ of Coreopsis lanceolata, Vitex negundo and Bidens frondosa were measured by LI-6400-40 B under controlled CO2 concentrations and temperatures, then light-response curves of ETR-I and（37）PSⅡ-I were simulated by a mechanistic model, a negative exponential model and an exponential model, respectively. Important findings The fitted results showed that ETR-I and（37）PSⅡ-I data of the three plants fit well to the three models. However, the saturation light intensity（PARsat） and maximum efficiency of photosystem Ⅱ（Fv/Fm） estimated by exponential model for ETR-I and（37）PSⅡ-I were greatly different from the measured data. Moreover, the mechanistic model revealed that the ΦPSⅡ for the three species decreased with increasing I as the effective light energy absorption cross-section of light-harvesting pigments decreased. At the same time, it showed that（37）PSⅡ depended not only on I, but also on eigen-absorption cross-section of light-harvesting pigment, efficiency of exciton, photochemical constant, heat dissipation constant and average lifetime of light-harvesting pigment-protein complex in the lowest state.

关 键 词：光系统Ⅱ 实际光化学量子效率 电子传递速率 机理模型 天线色素分子 

分 类 号：Q945.11[生物学—植物学]