植物光合作用的多样性

植物光合作用的多样性文宗（四川省成都市第七中学,６１００１５）光合作用既是生物学中最古老的问题,也是当前生物学的前沿之一,因为它不仅在农业,能源,生态等问题中具有重大实际意义,而且在生命起源,进化与光能转换等生物学基本理论问题中也很重要。但自１７７１...     

中国科学院植物研究所光合作用与环境分子生理学重点实验室简介

责任编辑:孙冬花一、实验室概况中国科学院植物研究所光合作用与环境分子生理学重点实验室成立于2001年。由原“光合作用基础研究开放实验室”和“资源植物分子与发育生物学开放实验室”整合而成。实验室主要研究方向是光合作用高效转能的分子机理及蛋白质组学、植物对环境信号应答的功能基因组学和植物次生代谢分子调控与基因工程。重点实验室建立了功能基因组学、蛋白质组学、细胞生物学和生化分析等技术平台,拥有基因芯片工作站、蛋白质谱仪、激光共聚焦显微镜、电子显微镜和高效液相色谱仪等大型设备。现有15个研究组,科研人员80余人,博…     

光合作用的“午睡”现象

作物经济产量的高低,主要取决于叶片面积的大小,光合速率的高低和光合时间的长短及分配到有重要经济价值的器官中的光合产物的多少。因此,光合速率是人们非常重视的一个产量构成因素。在一天当中,随着环境条件的变化,叶片的光合速率往往发生规律性的变化。通常,光合速率早晚低而中午高,其日变化进程和太阳幅射强度的变化相类似,是一条单峰曲线。然而,在空气温度高,湿度小而阳光充足的夏季晴天,许多植物的光合日变化进程是一条双峰曲线,上下午各有一个高峰,而中午有一个低谷。这种光合速率的中午降低现象,人们常称之为光合作用…     

青海高原植物生理生态学研究：Ⅱ.高寒草甸植物的光合作用

青海高原高寒草甸植物柔软紫苑和糙毛鹅冠草,在同一海拔高度（３２００ｍ）,由于种的不同,净光合速率和表观光合量子效率（ＡＱＹ＝１／ＡＱＲ）也不同。双子叶植物柔软紫苑较单子叶植物糙毛鹅冠草高一些。同一垂穗披碱草,而在不同海拔高度（２３００ｍ和３２００ｍ）,由于海拔和气压不同,Ｐｎ和ＡＱＹ也不同。在高海拔地区（３２００ｍ）,长期生长的垂穗披碱草的Ｐｎ和ＡＱＹ较低海拔地区（２３００ｍ）同一植物的低,在青海     

光合作用气孔限制分析中的一些问题

简要分析评论了光合作用气孔限制分析中的一些似是而非的观念及其作法的不可靠性。     

光合作用的光抑制

虽然光是植物光合作用的根本推动力,没有光植物便不能进行光合作用,光不足则不能高速地进行光合作用,可是光过剩对植物来说也不是好事。当叶片接受的光能超过它所能利用的量时,光可以引起光合活性的降低。这就是光合作用的光抑制现象。它的最明显特征是光合效率的降低。在没有其它环境胁迫的条件下,晴天中午许多植物冠层表面的叶片和静止的水体表层的藻类经常发生光抑制。由于发生光抑制的前提是光能过剩,所以,任何妨碍光合作用正常进行而引起光能过剩的因素,如低温、干旱等,都会使植物易于发生光抑制。因此,在两种或两种以上环境…     

从植物生理学谈光合作用与农业生产和粮食安全

目前,粮食安全问题已经成为了国家相关部门高度重视的一项问题,其不仅关系到社会经济的稳定发展,而且对人们生活生产也具有重要作用。我们都知道,当前我国所食用的食物都是光合作用的产物,因此,光合作用对农业生产和粮食安全的作用是不容忽视的。本文首先对植物生理学进行简要概述,并在此基础上对光合作用与农业生产和粮食安全进行介绍,以此来为今后我国粮食安全目标的实现提供一定的参考依据。     

关于卡尔文循环的图解

卡尔文循环（Calvincycle）是植物生理学教材中光合作用一章的教学重点和难点。因其涉及的代谢反应错综复杂，教学中往往要用图解加以说明，从而增强教学的直观性，便于理解和掌握。收槁199个10叫0但是，从现有教材中的循环图解来看，存在线条比较杂乱、各代谢物间的数量关系不     

气孔不均匀关闭与光合作用的非气孔限制

简要评述气孔不均匀关闭现象的诱发因素和气孔不均匀关闭与光合作用的非气孔限制假象的关系以及几种检测气孔不均匀关闭的方法。     

Effects of Irradiance and Temperature on the Photosynthesis and Vegetative Propagation of Caulerpa serrulata

The photosynthetic oxygen evolution of Caulerpa serrulata was determined with oxygen electrodes. The effects of light and temperature on the growth and regeneration of fragmented C. serrulata thalli were analyzed. The regenerating rate and establishment of different sizes and portions of C. serrulata were studied. The results showed that the light saturation point of C. serrulata was 200 μmol photons/m^2 per s and the optimum growth temperature was 25-30 ℃. Under these conditions, the maximum photosynthetic oxygen evolution rate was 15.1 ± 0.29 mg O2/mg Chl alh, the growth rate and elongation rate reached the highest values, 4.67 ±0.09 mg FW/d and 0.78± 0.01 mm/d, respectively. The fragmented C. serrulata thalli was regenerated at 20-35℃ and survived at 15℃ and 200 μmol photons/m^2 per s. A different survival rate was detected according to fragment size. All of these results indicated that C. serrulata was a candidate to become an invasive species if introduced into a new place. Therefore, we should pay more attention to C. serrulata for its potential threat to marine ecosystem when it is sold for aquarium use.     

Methods for Analysis of Protein Glutathionylation and their Application to Photosynthetic Organisms

Protein S-glutathionylation, the reversible formation of a mixed-disulfide between glutathione and protein thiols, is involved in protection of protein cysteines from irreversible oxidation, but also in protein redox regulation. Recent studies have implicated S-glutathionylation as a cellular response to oxidative/nitrosative stress, likely playing an important role in signaling. Considering the potential importance of glutathionylation, a number of methods have been developed for identifying proteins undergoing glutathionylation. These methods, ranging from analysis of purified proteins in vitro to large-scale proteomic analyses in vivo, allowed identification of nearly 200 targets in mammals. By contrast, the number of known glutathionylated proteins is more limited in photosynthetic organisms, although they are severely exposed to oxidative stress. The aim of this review is to detail the methods available for identification and analysis of glutathionylated proteins in vivo and in vitro. The advantages and drawbacks of each technique will be discussed as well as their application to photosynthetic organisms. Furthermore, an overview of known glutathionylated proteins in photosynthetic organisms is provided and the physiological importance of this post-translational modification is discussed.     

Construction of a chloroplast protein interaction network and functional mining of photosynthetic proteins in Arabidopsis thaliana

Chloroplast is a typical plant cell organelle where photosynthesis takes place. In this study, a total of 1 808 chloroplast core proteins in Arabidopsis thaliana were reliably identified by combining the results of previously published studies and our own predictions. We then constructed a chloroplast protein interaction network primarily based on these core protein interactions. The network had 22 925 protein interaction pairs which involved 2 214 proteins. A total of 160 previously uncharacterized proteins were annotated in this network. The subunits of the photosynthetic complexes were modularized, and the functional relationships among photosystem Ⅰ （PSI）, photosystem Ⅱ （PSII）, light harvesting complex of photosystem Ⅰ （LHC Ⅰ） and light harvesting complex of photosystem Ⅰ （LHC Ⅱ） could be deduced from the predicted protein interactions in this network. We further confirmed an interaction between an unknown protein AT1G52220 and a photosynthetic subunit PSI-D2 by yeast two-hybrid analysis. Our chloroplast protein interaction network should be useful for functional mining of photosynthetic proteins and investigation of chloroplast-related functions at the systems biology level in Arabidopsis.     

Induction of the AOX1D Isoform of Alternative Oxidase in A. thaliana T-DNA Insertion Lines Lacking Isoform AOX1A Is Insufficient to Optimize Photosynthesis when Treated with Antimycin A

Plant respiration is characterized by two pathways for electron transfer to O2, namely the cytochrome pathway （CP） that is linked to ATP production, and the alternative pathway （AP）, where electrons from ubiquinol are directly transferred to O2 via an alternative oxidase （AOX） without concomitant ATP production. This latter pathway is well suited to dispose of excess electrons in the light, leading to optimized photosynthetic performance. We have characterized T- DNA-insertion mutant lines of Arabidopsis thaliana that do not express the major isoform, AOXIA. In standard growth conditions, these plants did not show any phenotype, but restriction of electron flow through CP by antimycin A, which induces AOXIA expression in the wild-type, led to an increased expression of AOXID in leaves of the aoxla-knockout mutant. Despite the increased presence of the AOX1D isoform in the mutant, antimycin A caused inhibition of photosyn- thesis, increased ROS, and ultimately resulted in amplified membrane leakage and necrosis when compared to the wild- type, which was only marginally affected by the inhibitor. It thus appears that AOX1 D was unable to fully compensate for the loss of AOXIA when electron flow via the CP is restricted. A combination of inhibition studies, coupled to metabolite profiling and targeted expression analysis of the P-protein of glycine decarboxylase complex （GDC）, suggests that the aoxla mutants attempt to increase their capacity for photorespiration. However, given their deficiency, it is intriguing that increase in expression neither of AOX1D nor of GDC could fully compensate for the lack of AOXIA to optimize pho- tosynthesis when treated with antimycin A. We suggest that the aoxla mutants can further be used to substantiate the current models concerning the influence of mitochondrial redox on photosynthetic performance and gene expression.     

Comparative Genomic Study of the Thioredoxin Family in Photosynthetic Organisms with Emphasis on Populus trichocarpa

The recent genome sequencing of Populus trichocarpa and Vitis vinifera, two models of woody plants, of Sorghum bicolor, a model of monocot using C4 metabolism, and of the moss Physcomitrella patens, together with the availability of photosynthetic organism genomes allows performance of a comparative genomic study with organisms having different ways of life, reproduction modes, biological traits, and physiologies. Thioredoxins （Trxs） are small ubiq- uitous proteins involved in the reduction of disulfide bridges in a variety of target enzymes present in all sub-cellular compartments and involved in many biochemical reactions. The genes coding for these enzymes have been identified in these newly sequenced genomes and annotated. The gene content, organization and distribution were compared to other photosynthetic organisms, leading to a refined classification. This analysis revealed that higher plants and bryo- phytes have a more complex family compared to algae and cyanobacteria and to non-photosynthetic organisms, since poplar exhibits 49 genes coding for typical and atypical thioredoxins and thioredoxin reductases, namely one-third more than monocots such as Oryza sativa and S. bicolor. The higher number of Trxs in poplar is partially explained by gene duplication in the Trx m, h, and nucleoredoxin classes. Particular attention was paid to poplar genes with emphasis on Trx-like classes called Clot, thioredoxin-like, thioredoxins of the lilium type and nucleoredoxins, which were not described in depth in previous genomic studies.     

NADPH Thioredoxin Reductase C Controls the Redox Status of Chloroplast 2-Cys Peroxiredoxins in Arabidopsis thaliana

Chloroplast 2-Cys peroxiredoxins （2-Cys Prxs） are efficiently reduced by NADPH Thioredoxin reductase C （NTRC）. To investigate the effect of light/darkness on NTRC function, the content of abundant plastidial enzymes, Rubisco, glutamine synthetase （GS）, and 2-Cys Prxs was analyzed during two consecutive days in Arabidopsis wild-type and ntrc mutant plants. No significant difference of the content of these proteins was observed during the day or the night in wildtype and mutant plants. NTRC deficiency caused a lower content of fully reduced 2-Cys Prxs, which was undetectable in darkness, suggesting that NTRC is the most important pathway for 2-Cys Prx reduction, probably the only one during the night. Arabidopsis contains two plastidial 2-Cys Prxs, A and B, for which T-DNA insertion lines were characterized showing the same phenotype as wild-type plants. Two-dimensional gel analysis of leaf extracts from these mutants allowed the identification of basic and acidic isoforms of 2-Cys Prx A and B. In-vitro assays and mass spectrometry analysis showed that the acidic isoform of both proteins is produced by overoxidation of the peroxidatic Cys residue to sulfinic acid. 2-Cys Prx overoxidation was lower in the NTRC mutant. These results show the important function of NTRC to maintain the redox equilibrium of chloroplast 2-Cys Prxs.     

Roles of Thioredoxins in the Obligate Anaerobic Green Sulfur Photosynthetic Bacterium Chlorobaculum tepidum

Thioredoxin is a small ubiquitous protein that is involved in the dithiol-disulfide exchange reaction, byway of two cysteine residues located on the molecule surface. In order to elucidate the role of thioredoxin in Chlorobaculum tepidurn, an anaerobic green sulfur bacterium that uses various inorganic sulfur compounds and H2S as electron donors under strict anaerobic conditions for growth, we applied the thioredoxin affinity chromatography method （Motohashi et al., 2001）. In this study, 37 cytoplasmic proteins were captured as thioredoxin target candidates, including proteins involved in sulfur assimilation. Furthermore, six of the candidate proteins were members of the reductive tricarboxylic acid cycle （pyruvate orthophosphate dikinase, pyruvate flavodoxin/ferredoxin oxidoreductase, ~-oxoglutarate synthase, citrate lyase, citrate synthase, malate dehydrogenase）. The redox sensitivity of three enzymes was then examined： citrate lyase, citrate synthase, and malate dehydrogenase, using their recombinant proteins. Based on the information relating to the target proteins, the significance of thioredoxin as a reductant for the metabolic pathway in the anaerobic photosynthetic bacteria is discussed.     

细胞核,细胞质基因与光合作用的关系

光合作用受细胞核及细胞质基因组垢共同控制。参与叶绿素,类胡萝卜素合成和光合作用过程的许多酶都由核基因控制,而光合电子传递体大部分受核基因控制,少部分受细胞质基因控制。光合作用过程包括光反应与暗反应两个阶段。光反应发生在类囊体膜上,而类囊体膜４个组成部分细胞核,持基因共同编码。在暗反应中,催化ＣＯ２固定的关键酶核酮糖二磷酸羧化酶／加氧酶由大,小亚基组成,大亚基由叶绿体基因编码;小亚基由核基因控制。