低剂量UV-B辐射对乌拉尔甘草叶片光合机构的影响

Photosynthetic Apparatus in Leaves of Glycyrrhiza uralensis under Low Level UV-B Radiation

为了探讨植物叶片对UV-B辐射增强的响应机制,采用叶绿素荧光测定技术,分别测定在人工模拟低剂量UV-B(2.4μW/cm^2)辐射条件下乌拉尔甘草叶片的叶绿素荧光诱导动力曲线、初始荧光(F_0)、最大荧光(F_m)、光合机构比活性参数(ABS/RC、TR_o/RC和ET_o/RC)和性能指数等变化规律。结果表明:(1)低剂量UV-B辐射未引起甘草叶片O-J-I-P叶绿素荧光诱导曲线中的相数发生改变,UV-B辐射对PSⅡ的影响主要发生在其受体侧,而非供体侧;(2)低剂量UV-B辐射引起了甘草叶片光合系统F_v/F_m以及F_m、F_0的明显变化,同时也影响了光合机构的开放程度和电子从Q_A向Q_B传递效率,从而影响了光转化效率;相应性能指数(PI_(abs)和PI_(total))的改变亦验证了此结果。研究认为,低剂量UV-B辐射抑制乌拉尔甘草叶片光合系统Ⅱ受体侧Q_A至PQ之间的电子传递效率,从而影响了Q_A之后的光化学反应及非光化学反应。

To investigate the response of photosynthetic apparatus to UV-B radiation,we investigated the changes of chlorophyll fluorescence parameters under artificial simulated low UV-B radiation treatment（2.4μW/cm^2）,that including Chl a fluorescence transients induced dynamic curve,F_0,F_m,the parameters of PSⅡreaction center activity（ABS/RC,TR_o/RCand ET_o/RC）and performance index（PI）in leaves of Glycyrrhiza uralensis,by using the pocket PEA.The results suggested that：（1）UV-B mainly influenced the acceptor side of PSⅡ system rather than its donor side because of the O-J-I-P chlorophyll fluorescence induction curves didn＇t change by low level UV-B radiation.（2）The results of F_0,F_mand F_v/F_mindicated that UV-B radiation inhibited the openness of reaction center and blocked the transporting of electron from Q_Ato Q_B,and that was confirmed by the decreasing of PI_（abs）and PI_（total）.Thus,low level UV-B radiation influences photochemical or non-photochemical reaction beyond Q_Aas result of reduced electron transportation efficiency from Q_Ato PQ.