【摘要】 增强的紫外线-B(ultraviolet-B,UV-B)辐射对植物生长具有抑制效应的观点已被广泛接受,而低剂量的UV-B辐射是否也可像其它弱胁迫一样促进植物的光合作用,目前还不清楚。本研究运用荧光光谱技术,针对在低剂量UV-B辐射环境中生长的植物,分析其光系统Ⅱ(photosystemⅡ,PSⅡ)中能量吸收及传递的过程。稳态荧光激发及发射光谱显示,增强的低剂量UV-B辐射使荧光发射强度增加,并改变了各个高斯光谱组分的比例。7天的UV-B辐射,使捕光色素蛋白复合物(light-harvesting complexⅡ,LHCⅡ)吸收的大部分能量传递到反应中心(reaction center,RC),是对照组的近两倍。对照组和UV-B处理组的超快荧光动力学曲线拟合结果都得到3组时间组分:小于100 ps,几百ps及几个ns。荧光谱高斯解析及荧光动力学曲线时间拟合结果表明,低剂量的UV-B辐射加快了PSⅡ中LHCⅡ向RC的能量传递,并使传递到RC的能量增加,这将有助于植物的生长。说明低剂量UV-B辐射作为一种弱胁迫,提高了植物利用能量的效率。该结果有助于全面了解UV-B辐射对植物生长,尤其是对其光合作用过程的影响及其机制。更多还原

【Abstract】 Inhibited effect of ultraviolet-B(UV-B) on plant growth has been accepted widely,while whether low dose UV-B radiation could be a stimulator accelerating photosynthesis of plant just like other stress is still unknown.The influence of low-level UV-B radiation on primary energy transfer progress of photosystem Ⅱ(PS Ⅱ) was studied with fluorescence spectrum technology.The increase of fluorescence intensity in UV-B experiment group was observed by steady-state fluorescence excitation and emission spectra.We found that the proportion of Gauss deconvolution spectrum component of emission spectra were altered by UV-B irradiation,and the most part of energy absorbed by LHCII was transferred to RC under 7-d UV-B radiation,which was the twice as the control.Moreover,ultrafast fluorescence decay curve of control and UV-B groups were analyzed by three groups of time component:less than 100 picoseconds,several hundreds picoseconds and several nanoseconds.The results of Gauss deconvolution component and fluorescence dynamic curve indicate that low dose UV-B radiation speed up energy transfer from light-harvest antenna to reaction center of PSII,and increase energy distribution to reaction center at the same time.It will be benefit for promotion of plant growth.All these results illustrate that low-level UV-B radiation could be a kind of low-level stress to raise energy utilization efficiency of PSII.These results can help us to fully understand the effect of UV-B radiation on plant growth,especially the influence of photosynthesis process and its mechanism.更多还原