NaCl 胁迫对盐芥和拟南芥光合作用的影响

本研究检测了与盐芥(Ghellungiella halophila)和拟南芥(Arabidopsis thaliana)光合作用相关的叶绿素、净光合速率(photosynthetic rate, Pn)、气孔导度(stomatal conductance, Gs)、胞间隙CO2浓度以及叶绿素荧光参数等指标, 观察到随着NaCl浓度逐渐增加, 盐芥的叶绿素a/b值(Chl a/Chl b)、类胡萝卜素/总叶绿素值(Car/Chl)显著高于拟南芥, 且二比值变化幅度较小并保持较高水平。盐胁迫下拟南芥净光合速率下降、气孔导度下降和胞间CO2浓度减小。气孔因素是引起拟南芥光合能力下降的主要因素。叶绿素荧光参数的变化表明, 50-200 mmol.L-1 NaCl降低拟南芥叶绿体对光能的吸收能力, 而且降低叶绿体的光化学活性, 使电子传递速率和光能转化效率大幅度下降,造成光能转化为化学能的过程受阻,进一步加剧了光合放氧和碳同化能力的降低。而50-200 mmol.L-1 NaCl 胁迫没有使盐芥的光合作用受到不良影响。

Response of Photosynthesis Function of Salt Cress and Arabidopsis to NaCl Salt Stress

This paper covers study of the response of photosynthetic function of salt cress (Ghellungiella halophila) and Arabidopsis seedlings in NaCl salt stress. The ratios of Chl a/Chl b and Car/Chl increased in salt-cress seedlings with increasing salt concentration level but were significantly higher in salt cress than in Arabidopsis. The photosynthetic rate (Pn) did not decline in salt cress seedling leaves, and Pn was enhanced at lower NaCl concentrations, but the Pn, Gs and Ci values were decreased in Arabidopsis leaves with increasing salt concentration; the stoma factor is the main reason for Arabidopsis leaves inhibiting photosynthesis function with salt stress. A concentration of 50-200 mmol.L-1 of salt stress greatly reduced the capacity of light energy and chloroplasts, electron transport rate of PSII, efficiency of primary conversion of light energy and the coefficient of photochemical fluorescence quenching (qP) in Arabidopsis leaves. The concentration also blocked the process of transforming light energy to chemical energy in photosynthesis function and led to decreased capacity of oxygen evolution and carbon assimilation. But salt cress leaves can overcome these restrictions, and the photosynthesis function was not destroyed seriously.