光合作用与农业生产

光合作用被誉为是地球上最重要的化学反应,没有光合作用就不可能有人类社会的产生和发展。光合作用是作物产量形成的物质基础,如何充分利用太阳能进行光合作用是农业生产中的一个根本性问题。文章从作物光能利用率与光合作用效率、光合作用过程及其运转的调控、农业发展动向与高光效三个方面简要分析了光合作用与农业生产的关系,以期为今后的相关研究提供一些思考。     

光合作用在世纪之交的研究动向

当前光合作用的研究动向大致可分为３个方面：１）深入探讨光合作用反应机理,结构功能,特别是关于从水分子释放出氧气的过程和腺三磷的合成机理;２）了解光合机构的组装,运转与调节,包括叶绿体有关组分的生物合成与组装,光合作用各部分反应间的弹性衔接和协调,光合机构的运转与植物其它生命活动的配合及对环境变动的适应,在分子水平上进行生理研究等;３）研究与光合作用有关的生产实践上的重大问题,如农业生产和生态环境的     

光合机构的调节和运转

光合作用机理研究和生理研究正在互相接近,在其接合处形成了一个探讨光合机构运转与调节的活跃领域。本文极简要地叙述了中国科学院上海植物生理研究所对这个问题的研究进展。内容包括：光合作用各部分反应的配合与协调、光合作用与植物其它生命活动的联系、光合机构对主要环境因素变动的响应和适应等方面的主要工作。     

柑橘属光合作用的环境调节

光合机构的运转受环境影响很大,与柑橘的生长发育、产量和品质密切相关.结合我们的工作,综合论述了柑橘光合作用环境调节的研究进展.强光和紫外光导致光合作用下降与PSⅡ反应中心失活有关,光呼吸和叶黄素循环对光合机构有保护作用.温度胁迫下,光合作用下降主要是RuBPCase活性下降和PSⅡ反应中心失活引起,品种间存在差异.轻度水分胁迫引起的光合作用下降是气孔限制的结果,而严重水分胁迫导致光合作用的非气孔限制.提高CO₂浓度,能够促进柑橘的光合作用,进而促进柑橘的生长和提高其品质.阐述了N、P、S、Fe等矿质元素调节光合作用的机理及盐胁迫对光合作用的影响,指出了今后柑橘光合作用的研究方向.     

极地和深海环境中低温噬菌体研究进展

极地和深海是地球上较为独特的生态系统,生活在其中的生物由于长期处于低温、寡营养和黑暗封闭的环境中,大多缺乏基本的光合作用,而被认为是研究生命进化和地球环境演化等问题的＂活化石＂。在这样的极端环境中,低温噬菌体的丰度却很高,越来越多的证据表明它们在维持这类环境的生态平衡和调控生物地球化学循环等方面扮演着非常重要的角色。对极地与深海中低温噬菌体的研究进行简要综述。     

光合作用研究历程中的重大事件(1)

光合作用是植物特有的生理功能,是“地球上最重要的化学反应”,光合作用研究对于生命科学及人类未来具有重大意义。经过科学工作者长期艰苦的研究,对光合作用有了多方面的相当了解。综述了发生在光合作用研究历程中的重大事件,为生物学教学提供补充资料。     

3-磷酸甘油醛脱氢酶的分子遗传

3-磷酸甘油醛脱氢酶(D-glyceraldehyde-3-pho-sphate dehydrogenase,GAPDH)是糖酵解、糖异生及光合作用碳固定循环过程中的关键酶,充当蛋白质结构与功能研究的重要材料,其基因也越来越多地应用于分子遗传学的研究领域中。由于糖酵解和光合作用是细胞古老的能量代谢形式,GAPDH的基因也在进化的早期出现。在漫长的     

2001年全国植物光合作用、光生物学及其相关的分子生物学 学术研讨会征文通知

中国植物生理学会、中国生物物理学会和中国植物学会联合组办 ,广西师范大学生物系承办的全国植物光合作用、光生物学及相关分子生物学研讨会拟于 2 0 0 1年 10月下旬在广西桂林市召开 .会议征文内容 :1 植物光合作用 :原初反应与放氧、光合膜蛋白复合体的结构与功能、电子与质子传递、光合碳代谢、光合生理生态、光合机理的运转与调节、光合作用与作物生产力关系等 ;2 光生物学 :生物系统的光物理与光化学、光医学、环境光生物学、生物发光及其新分析技术与新方法等 ;3 植物分子生物学与生物技术 :光合作用的分子生物学、关键发育过程的分…     

20 0 1年全国植物光合作用、光生物学及其相关的分子生物学学术研讨会征文通知

中国植物生理学会、中国生物物理学会和中国植物学会联合组办 ,广西师范大学生物系承办的全国植物光合作用、光生物学及相关分子生物学研讨会拟于 2 0 0 1年 1 0月下旬在广西桂林市召开 .会议征文内容 :1 植物光合作用 :原初反应与放氧、光合膜蛋白复合体的结构与功能、电子与质子传递、光合碳代谢、光合生理生态、光合机理的运转与调节、光合作用与作物生产力关系等 ;2 光生物学 :生物系统的光物理与光化学、光医学、环境光生物学、生物发光及其新分析技术与新方法等 ;3 植物分子生物学与生物技术 :光合作用的分子生物学、关键发育过程的…     

光合作用测定及研究中一些值得注意的问题

随着科学研究的深入和现代化光合测定系统的推广,越来越多的植物生理学和植物生态学以及农学、林学、园艺学和遗传学的研究均涉及叶片光合作用的测定。用于叶片光合测定的仪器种类和数量越来越多。这类仪器的使用简便、快捷,几乎人人都能使用,即使对光合作用一无所知的人也可以用它在2min内测得一组光合速率及有关的参数。然而,尽管使用这类仪器的人很多,但能利用所得资料写出高水平科学论文的人却很少。其中的原因主要的可能是使用者缺乏足够的有关光合作用的背景知识和测定及研究经验,测定方法不当,所得结果不可靠：或者实验设计不合理,难以说明问题;或者是对相关研究现状不清楚,不能明确地提出科学问题;或者是对光合作用的基础知识知之太少,不能对所得结果作出恰当的分析与解释。这几种情况也许兼而有之。为了充分发挥这类现代化但价格昂贵的仪器的作用,将光合作用研究推向深入,这里将光合测定与研究中一些常见的问题提出来,以引起初学者们的注意。     

Can photosynthesis provide a `biological blueprint'' for the design of novel solar cells?

The primary photochemical reactions in purple-bacterial photosynthesis take place in discrete, membrane-bound pigment–protein complexes called reaction centres and light-harvesting complexes. The detailed information on their structure and function now available is being used to aid the design and construction of novel solar-energy converters.     

Solar‐to‐Hydrogen Energy Conversion Based on Water Splitting

Artificial photosynthesis provides a blueprint to harvest solar energy to sustain the future energy demands. Solar‐driven water splitting, converting solar energy into hydrogen energy, is the prototype of photosynthesis. Various systems have been designed and evaluated to understand the reaction pathways and/or to meet the requirements of potential applications. In solar‐to‐hydrogen conversion, electrocatalytic hydrogen and oxygen evolution reactions are key research areas that are meaningful both theoretically and practically. To utilize hydrogen energy, fuel cell technology has been extensively investigated because of its high efficiency in releasing chemical energy. In this review, general concepts of the photosynthesis in green plants are discussed, different strategies for the light‐driven water splitting proposed in laboratories are introduced, the progress of electrocatalytic hydrogen and oxygen evolution reactions are reviewed, and finally, the reactions in hydrogen fuel cells are briefly discussed. Overall, the mass and energy circulation in the solar‐hydrogen‐electricity circle are delineated. The authors conclude that attention from scientists and engineers of relevant research areas is still highly needed to eliminate the wide disparity between the aspirations and realities of artificial photosynthesis.     

同位素示踪技术在光合作用研究中的应用

利用同位素示踪技术可以掌握物质在化学反应中运行和变化情况。试论述同位素示踪技术在研究光合作用中的多种应用：提示光合作用中几种元素的转变方向;判断光合作用的反应场所和反应条件;推断光合作用的反应过程;检验产物的运输方向;研究光合作用与呼吸作用的关系。     

光合作用研究进展:从分子机理到绿色革命

根据国际科学期刊Nature,Science和PhotosynthesisResearch等近年发表的60多篇文献评论了过去5年来光合作用研究领域的研究进展.这篇评论由光合机构的精细结构与光合作用的反应机理、光合作用的调节机制与环境胁迫和光合机理知识的应用与绿色革命三部分组成.第一部分包括天线和反应中心的结构、放氧机理和ATP合成的分子机理;第二部分涉及二磷酸核酮糖羧化酶/加氧酶,光抑制,氧化还原调节和光合作用的高温抑制;第三部分讨论新绿色革命的特点和艰巨性,指出新绿色革命的中心问题是作物光合效率的改善,锐利武器是基因工程,新绿色革命的成功有赖于对光合作用的深入理解和分子生物学家、植物生理学家、生物化学家与农学家们的协同努力.     

Enhanced Thermal Energy Dissipation Depending on Xanthophyll Cycle and D1 Protein Turnover in Iron-Deficient Maize Leaves Under High Irradiance

Pigment contents of chloroplasts and net photosynthetic rate were dramatically reduced in maize leaves suffering from iron deficiency. However, the reduction in photosynthesis was probably not caused by decreased contents of chlorophylls and carotenoids and by photon absorption; the primary limiting factor for photosynthesis may rather be the decrease of electron transport activity in photosystem 1. Iron-deficient leaves suffered serious acceptor-side photoinhibition, and more than 60 % of absorbed photons were dissipated, while less than 40 % was used in photochemical reaction. Thermal energy dissipation depending on xanthophyll cycle and D1 protein turnover was enhanced when acceptor-side photoinhibition occurred in iron-deficient maize leaves.     

Excited chlorophyll and related problems

A historical outline is presented of the primary light energy conversion in photosynthesis studied by our research group. We found that photoexcited chlorophylls, pheophytins and porphyrins are capable of reversible and irreversible oxido-reduction. The mechanism of the photosensitized electron transfer from donor to acceptor molecule is based on the reversible photochemical oxido-reduction of the pigment-sensitizer. This property of the excited pigments is realized in the reaction centres of photosynthetic cells when photooxidation of bacteriochlorophyll(s) or chlorophyll of Photosystem II is coupled to pheophytin reduction leading to the final charge separation.The studies of the state and function of pigments in the course of chlorophyll biosynthesis in cellular and non-cellular systems revealed different monomeric and aggregated forms of pigments and the phenomenon of self-assembly of various forms of chlorophylls, bacteriochlorophylls and protochlorophylls. The discovery of protochlorophyll photoreduction in non-cellular system allowed the study of the molecular mechanisms of this reaction.In order to construct models of photosynthetic charge separation, we used inorganic photocatalysts-semiconductors, mainly titanium dioxide, and pigments incorporated into detergent micelles or lipid vesicles. To prevent back reactions we used heterogeneous systems where primary unstable products were spatially separated; coupling of solubilized chlorophylls or semiconductor particles with bacterial hydrogenase led to molecular hydrogen photoproduction. Light excitation of some coenzymes, mainly NADH and NADPH, was considered from the point of view of early events of chemical evolution.Now we are interested in the creation of photobiochemical systems using principles of photosynthesis for the conversion and storage of solar energy.Written at the invitation of Govindjee.     

Some effects of 2537 A on green algae and chloroplast preparations

1. The kinetics of the inactivation of photosynthesis by 2537 A in Chlorella pyrenoidosa and Scenedesmus D(1) indicate that, while the destruction process is largely a first order effect, higher order effects also occur, which become evident at low exposures. In agreement with previous observations, endogenous respiration is insensitive to exposures which inactivate photosynthesis. 2. In Scenedesmus D(1) a solid dose of ultraviolet has no more effect on the photosynthetic apparatus than a dose of equal total duration interrupted by periods of photosynthesis. Nor is any difference noted if the cells are in a different buffer, e.g. 0.05 M KH(2)PO(4), or carbonate-bicarbonate buffer 9. 3. In C. pyrenoidosa, a solid dose and an interrupted dose cause equal effects on photosynthesis when neutral phosphate buffer is used. If the ultraviolet exposure schedules are identical, equal effects are also noted in cells suspended in buffer 9, and in 0.05 M phosphate (pH 6.2). Solid exposures are, however, much more effective than interrupted exposures, when buffer 9 is used. 4. Oxygen evolution (Hill reaction), photosynthesis, and photoreduction in Scenedesmus D(1) are equally sensitive to a given dose of ultraviolet. The mechanism responsible for adaptation to hydrogen metabolism is not more sensitive to ultraviolet than is the photosynthetic mechanism. The O(2)/H(2)/CO(2) reaction in darkness is less sensitive to ultraviolet than any of the above reactions. 5. Glucose oxidation by C. pyrenoidosa, and colony formation in Scenedesmus D(1) are far more sensitive to a given dose of ultraviolet than photosynthesis in these organisms. 6. The photosynthetic apparatus of C. pyrenoidosa is more sensitive to ultraviolet than that of Scenedesmus D(1). 7. The Hill reaction in chloroplast fragments is also inactivated by 2537 A by a first order process. Exposures which inactivate this reaction completely have no effect on polyphenol oxidase, cytochrome oxidase, or catalase in the same chloroplast preparation. 8. After irradiation, the survival of photosynthesis in Scenedesmus D(1) and of the Hill reaction in chloroplast fragments are independent of the light intensity used to measure these processes. 9. No significant changes occur in the ultraviolet absorption of chloroplasts after an exposure to 2537 A, which completely inactivates the Hill reaction.     

紫细菌光合机构及光合作用基因的表达调控

紫细菌是研究细菌光合作用的重要生物。介绍了紫细菌光合机构捕光色素蛋白复合体Ⅰ(light-harvesting I)、捕光色素蛋白复合体Ⅱ(light-harvesting II)和光化学反应中心(reaction center)的结构, 并探讨了其光合作用基因的转录调控机制, 重点阐述了PpsR/AppA系统对紫细菌光合作用基因的转录调控。