毛尖紫萼藓(Grimmia pilifera P. Beauv)PSII光化学效率对脱水和复水的响应

Photochemical analysis of PSII in response to dehydration and rehydration in moss Grimmia pilifer P.Beauv

利用快速叶绿素荧光动力学技术研究了毛尖紫萼藓脱水和复水过程中叶绿素荧光变化,结果显示在脱水过程中毛尖紫萼藓PSII的最大光化学效率(Fv/Fm)、光合机构电子传递的量子产额(ETo/ABS)、捕获的激子将电子传递到电子传递链中超过QA的其它电子受体的概率(ETo/TRo)、单位叶面积的反应中心的数量(RC/CSo)以及PSⅡ受体库(Area)对叶片含水量的响应等均存在相对含水量阈值。在阈值范围内脱水,对以上荧光参数影响不大,低于阈值后,各荧光参数值迅速下降,直至PSII反应中心完全关闭以及光化学过程结束。再复水后,毛尖紫萼藓光合机构的最大捕光效率、实际光化学效率、PSII反应中心受体侧的电子传递链以及反应中心均能得到快速而有效的恢复。表明一定时间内脱水不会对毛尖紫萼藓的光合器官造成严重伤害,光合系统仍维持在可恢复状态。

Chlorophyll-fluorescence was measured by a handy PEA fluorometer in moss Grimmia pilifera P. Beauv in response to dehydration and rehydration following 8 day desiccation, and the result indicates that a threshold of relative water content （RWC） exists in moss Grirnrnia pilifera P. Beanv in terms of all the analyzed values of Fv/Fm,ETo/ABS, ETo/TRo,Area and RC/CSo during dehydration. A little change of chlorophyll-fluorescence was observed during dehydration above the RWC threshold, but a dramatic decrease occurred when the RWC became lower than the threshold. Upon rehydration after 8 day dehydration, the values of Fv/Fm,ETo/ABS,ETo/TRo,Area and RC/CSo recovered very rapidly, indicating that the photosynthetic apparatus of the moss Grirnrnia pilifera P. Beanv was not badly damaged by the dehydration in the condition, and the damage was reversible.