【作者】 庞海河；

【导师】 祖元刚；

【作者基本信息】 东北林业大学 ， 植物学， 2010， 博士

【摘要】 平流层臭氧的减少会导致到达地球表面的紫外线-B (UV-B)辐射显著增强,增强UV-B辐射对生物体有明显的生物学效应。本文在温室的条件下,研究增补3.25μw·cm-2.nm-1(低剂量)和9.76μw·cm-2·nm-1(高剂量)UV-B辐射剂量,分别处理10d(短期)、30d(过渡期)和60d(长期)时对南方红豆杉形态、叶片超微结构、初生与次生代谢的影响,以此在不同层次探讨南方红豆杉对增强UV-B辐射的生态适应机制,同时筛选有利于南方红豆杉生长及紫杉醇合成积累的最佳UV-B辐射处理条件。主要结果如下：1、增强UV-B辐射对南方红豆杉的形态和生物量有显著影响,不同UV-B辐射剂量和处理时间也具有显著性差异。长期低剂量UV-B辐射处理南方红豆杉叶面积、二级分枝长和二级分枝数增加、生物量增多,而根冠比降低；长期高剂量UV-B辐射处理南方红豆杉比叶重增加、叶面积和二级分枝长减小、生物量和根冠比显著降低,说明低剂量UV-B辐射有利于南方红豆杉生长,而高剂量抑制南方红豆杉生长。2、增强UV-B辐射对南方红豆杉叶片超微结构有显著影响,不同UV-B辐射剂量和处理时间也具有显著性差异。长期低剂量UV-B辐射处理南方红豆杉叶片开启气孔密度和气孔开度增加、表皮细胞壁增厚、表皮附属物增加(如蜡质),而高剂量UV-B辐射处理叶片开启气孔密度降低、气孔下室较多颗粒物；UV-B辐射处理南方红豆杉叶片叶绿体数量减少,形态扭曲、变形,基粒片层少、排列紊乱,基粒和基质片层膨胀、产生空泡,嗜锇滴体积变大、数量增多。3、增强UV-B辐射对南方红豆杉的氧化胁迫及其抗氧化响应。增强UV-B辐射短期处理,导致南方红豆杉叶片羟基自由基含量增加、MDA含量升高,抗氧化酶和UV-B吸收化合物含量增加；但长期低剂量UV-B辐射处理南方红豆杉自由基和抗氧化物质与对照无显著差异,而高剂量处理伤害仍较重。4、增强UV-B辐射对南方红豆杉光合特征和初生代谢有显著影响,不同UV-B辐射剂量和处理时间也具有显著性差异。长期低剂量UV-B辐射处理南方红豆杉净光合速率、Fv/Fm和Fv/Fo以及可溶性糖含量显著增加；而长期高剂量UV-B辐射处理南方红豆杉净光合速率、Fv/Fm和Fv/Fo以及可溶性糖含量显著降低,但蛋白质显著增加。5、增强的UV-B辐射对南方红豆杉叶片紫杉烷类含量均有显著的影响,结合3种紫杉烷类含量的相关性分析,我们发现短期UV-B辐射处理时南方红豆杉叶片中紫杉醇含量的提高可能主要是由糖基化7-木糖基-10-去乙酰基紫杉醇生物转化而来,长期UV-B辐射处理时南方红豆杉叶片中紫杉醇含量的提高可能主要是紫杉醇的合成前体物10-去乙酰基巴卡亭Ⅲ生物转化而来。综合以上分析,我们得出如下结论：(1)UV-B辐射处理对南方红豆杉表型、生理生化以及超显微结构均有显著影响,而南方红豆杉通过调整形态学结构、增加抗氧化酶活性以及增加UV-B吸收化合物和蜡质的含量以抵御增强的UV-B辐射胁迫。(2)长期低剂量UV-B辐射处理促进南方红豆杉叶片开启气孔密度、气孔孔径,净光合速率、荧光参数(Fv/Fm和Fv/Fo)等显著增加,进而促使南方红豆杉生物量显著增加；而长期高剂量UV-B辐射处理则严重破坏南方红豆杉叶片叶绿体结构、降低净光合速率和荧光参数(Fv/Fm和Fv/Fo),进而导致南方红豆杉生物量显著减少。(3) UV-B辐射处理显著的促进南方红豆杉叶片中紫杉醇的结合态以及其合成前体向紫杉醇生物转化和积累。(4)长期低剂量UV-B辐射处理是有利于南方红豆杉的生长发育,尤其能显著促进南方红豆杉叶片中紫杉醇的合成积累的最佳UV-B辐射条件。更多还原

【Abstract】 The principal ultraviolet radiation absorbance occurs in the stratospheric ozone layer in earth’s atmosphere. The destruction of this layer, which is caused by ozone depletion, has lead to an increase in solar UV-B radiation (280-320 nm) reaching the Earth’s surface and produced potentially biological effect for plants in the earth.In this thesis, the effects of different dose and treatment time of supplementary UV-B radiation on the Taxus chinensis var. marei grown in the greenhouse were studied. The dose of supplementary UV-B radiation were 3.25μw·cm-2·nm-1(low dose) and 9.76μw·cm-2·nm-1(high dose), and the radiation time were 10d (short term),30d (transition period) and 60d (long term), individually. Then, the responses of morphous, physiology, biochemical and ultrastructural of T. chinensis var. marei responses to supplementary UV-B radiation were investigated. We revealed the adapted mechanism of this plant to UV-B radiation in the cell and subcellular level and optimized the best UV-B radiation conditions to promote the growth of T. chinensis var. marei and the accumulation of taxol.The main results are as follows:1. There were noticeable effects of supplementary UV-B radiation in morphous and biomass of T. chinensis var. marei. Meanwhile, a noticeable distinction among different UV-B radiation dose and different time were also observed. After the long and low dose UV-B radiation treatment, the leaf area, secondary branch length, secondary branch numbers and biomass were increased; the root:shoot was decreased. However, the leaf area, secondary branch length and biomass were all reduced in long and high dose UV-B radiation. The low dose UV-B radiation was better to the growth of T.chinensis var. marei, but the high dose UV-B radiation was adverse.2. There were noticeable effects of supplementary UV-B radiation to the leaf ultrastructure of T. chinensis var. marei, and also noticeable distinction among different UV-B radiation dose and different time. The stomata density and aperture, cell wall of epidermic cell and appendages of the leaf of T. chinensis var. marei under long and low dose UV-B radiation were markedly increased. However, the stomata density under long and high dose UV-B radiation was reduced, and there were more particulate matter in substomatic chambers. Besides, the chloroplasts were twisting, distorted, the arrangement in the lamellae of the grana and stroma was loose, disordered, bulged and produced cavity, the volume and numbers (high dose) of osmiophilic grain were increased apparently by supplementary UV-B radiation.3. The hydroxyl free radicals and MDA content were notably increased under short UV-B radiation; and the active of anti-oxidant enzymes and UV-B absorbing substances were improved to resist to oxidation stress. There were no remarked changes between low dose UV-B radiation and CK, but there were still seriously damage under high dose UV-B radiation.4. There were noticeable effects of supplementary UV-B radiation to photosynthesis, physiology and metabolism of T. chinensis var. marei, and noticeable distinction among different UV-B radiation dose and different time. The net photosynthetic rate, Fv/Fm, Fv/Fo and soluble sugar were raised markedly. However, the net photosynthetic rate, Fv/Fm, Fv/Fo and soluble sugar were descended remarkably, but the protein content was increased remarkably.5. There were noticeable effects of supplementary UV-B radiation to the taxanes content in the leaves of T. chinensis var. marei, and based on the correlative analysis of three taxanes content, we found that the increase of taxol content maybe mainly come from the bioconversion of 7-xyl-10-DAT in short term UV-B radiation, but which maybe mainly come from the bioconversion of 7-xyl-10-DAT and 10-DAB long term UV-B radiation.The main conclusions are as follow:(1) There are observably effects of supplementary UV-B radiation to the morphology, physiology, biochemical and ultrastructural of T. chinensis var. marei. However, the plant could adapt to the UV-B radiation by changes of morphous architecture, increase of actives of anti-oxidant enzymes, UV-B absorbing substances and waxes content to resist to the UV-B stress. (2) Long term and low dose UV-B radiation could promote the stomata density and aperture, net photosynthetic rate, fluorescence parameters (Fv/Fm and Fv/Fo) to increase remarkably, and then the biomass is raised markedly. But the Long term and high dose UV-B radiation could injure the chloroplast configuration, inhibit net photosynthetic rate and fluorescence parameters(Fv/Fm and Fv/Fo), and then the biomass is reduced markedly (3) Supplementary UV-B radiation could promote notably the bioconversion of the combined taxol (7-xyl-10-DAT) and the precursor of taxol (10-DAB) to taxol. (4) The long term and low dose UV-B radiation are the best conditions to promote the growth and the accumulation of taxol.更多还原