摘要
报告了生长于热带林窗向阳处砂仁叶片叶绿素荧光参数的日变化 ,及阻止卷叶和用二硫苏糖醇(DTT)处理对它的影响。受强光照射 ,砂仁叶片迅速卷起。在雾天上午光强还相当弱 (低于 10 0 μmolm-2s-1)时 ,砂仁叶片就发生光抑制 ,中午最重 ,下午当光强减弱时 ,光抑制逐渐得到缓解。其热耗散 ( qN、NPQ)随光强的升高而增加 ,且下午仍在缓慢增加。阻止卷叶使强光下砂仁叶片光抑制加剧 ,Fo、NPQ升高。DTT处理也使光抑制加剧 ,Fo 升高 ,且使PSII反应中心发生可逆失活。夜间 2 3∶0 0各处理的荧光参数基本恢复。卷叶、叶黄素循环和PSII可逆失活 3种保护机制在同种植物中依次启动的现象尚属少见。
Amomum villosum Lour. (Zingeraceae) is a perennial herb that occurs in the understory of tropical and subtropical forests,and is an important medical plant.Its leaves naturally roll up upon exposure to bright sun.Its diurnal changes in fluorescence parameters were measured with a Hansatech Modulated Fluorometer (FMS2) under natural,preventing leaves from rolling and DTT (an inhibitor of xanthophyll cycle) treatment conditions in order to explore the protective strategy against photodamage.During the study period,it was foggy or overcast from midnight till 11∶30 am of next day and clear later; the plants were subject to sufficient moisture.The results showed that photoinhibition of A. villosum leaves occurred already in the foggy morning when the light intensity was lower than the photosynthetic light saturation point.The photoinhibition was accelerated with increase of incident light intensity, and recovery from it was in process gradually in the afternoon when light intensity decreased(Figs.1,2).In accordance,the non photochemical quenching rate was increased with an increase of incident light intensity.Preventing leaves from rolling accelerated photoinhibition(Figs.1,4).DTT treatment resulted in severer photoinhibition and reversible inactivation of photosystem two's (PSII) reaction center(Fig.4).Inactivated PSII may quench additional excessive absorbed light energy and down regulated its function so as to prevent it from photodamage.The fluorescence parameters under all above experimental conditions recovered nearly to the predawn levels at 23∶00(Table 1).This study reveals that leaf rolling,xanthophyll cycle and reversible inactivation of PSII are effective mechanisms for the protection against photodamage of photosynthetic apparatus of A. villosum .The three mechanisms start to function in sequence with increase of light stress.
基金
中国科学院"百人计划"资助项目部分研究内容
关键词
叶绿素荧光
光抑制
叶黄素循环
卷叶
PSⅡ
反应中心可逆失活砂仁
光破坏
叶片
中药材
chlorophyll fluorescence,photoinhibition of photosynthesis,xanthophyll cycle,leaf rolling,reversible inactivation of PSII reaction center, Amomum villosum Lour.
