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Metabolic repression of transcription in higher plants   总被引:75,自引:17,他引:58       下载免费PDF全文
J Sheen 《The Plant cell》1990,2(10):1027-1038
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Sink regulation of photosynthesis.   总被引:26,自引:0,他引:26  
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With rising level of CO2 in the atmosphere plants are expected to be exposed to higher concentration of CO2. Since, CO2 is a substrate limiting photosynthesis particularly in C3 plants in the present atmosphere, the impact of elevated CO2 would depend mainly on how photosynthesis acclimates or adjusts to the long term elevated level of CO2. Photosynthetic acclimation is a change in photosynthetic efficiency of leaves due to long term exposure to elevated CO2. This change in photosynthetic efficiency could be a biochemical adjustment that may improve the overall performance of a plant in a high CO2 environment or it could be due to metabolic compulsions as a result of physiological dysfunction. Acclimation has generally become synonymous with the word response, if long term exposure to elevated CO2 decreases the photosynthesis rate (Pn) at a given CO2 level, it is called negative acclimation, if it stimulates Pn at a given CO2 level, it is called positive acclimation. Photosynthetic acclimation is clearly revealed by comparing Pn of ambient and elevated CO2 grown plants at same level of CO2. Species level differences in acclimation to elevated CO2 have been reported. The physiological basis of differential photosynthetic acclimation to elevated CO2 is discussed in relation to the regulation of photosynthesis and photosynthetic carbon partitioning at cellular level.  相似文献   

5.
Little is known about the effect of hormones on the photosynthetic process. Therefore, we studied Rubisco content and expression along with gas exchange parameters in transgenic tobacco (Nicotiana tabacum) plants that are not able to sense ethylene. We also tested for a possible interaction between ethylene insensitivity, abscisic acid (ABA), and sugar feedback on photosynthesis. We measured Rubisco content in seedlings grown in agar with or without added sugar and fluridone, and Rubisco expression in hydroponically grown vegetative plants grown at low and high CO(2). Furthermore, we analyzed gas exchange and the photosynthetic machinery of transformants and wild-type plants grown under standard conditions. In the presence of exogenous glucose (Glc), agar-grown seedlings of the ethylene-insensitive genotype had lower amounts of Rubisco per unit leaf area than the wild type. No differences in Rubisco content were found between ethylene-insensitive and wild-type seedlings treated with fluridone, suggesting that inhibition of ABA production nullified the effect of Glc application. When larger, vegetative plants were grown at different atmospheric CO(2) concentrations, a negative correlation was found between Glc concentration in the leaves and Rubisco gene expression, with stronger repression by high Glc concentrations in ethylene-insensitive plants. Ethylene insensitivity resulted in plants with comparable fractions of nitrogen invested in light harvesting, but lower amounts in electron transport and Rubisco. Consequently, photosynthetic capacity of the insensitive genotype was clearly lower compared with the wild type. We conclude that the inability to perceive ethylene results in increased sensitivity to Glc, which may be mediated by a higher ABA concentration. This increased sensitivity to endogenous Glc has negative consequences for Rubisco content and photosynthetic capacity of these plants.  相似文献   

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彩叶植物叶片呈现不同的颜色主要是受遗传因素和外部环境的共同作用,揭示彩叶植物叶片呈色机制对选育彩叶植物新品种和彩叶植物的应用推广具有重要理论和实践意义。目前对彩叶植物呈色机制的研究主要集中于叶片中色素变化、光合特性、叶片结构和环境条件等方面。该文主要対近年来有关彩叶植物叶片中叶绿素代谢途径、类胡萝卜素代谢途径、次生代谢途径、光合作用和叶绿体发育相关结构基因和转录因子调控机制的研究进展进行综述,并对以后的研究方向进行了展望,为培育彩叶植物新品种提供了理论基础,也为人工调控叶色以及叶色的定向遗传改良提供了参考。  相似文献   

8.
Liska AJ  Shevchenko A  Pick U  Katz A 《Plant physiology》2004,136(1):2806-2817
Salinity is a major limiting factor for the proliferation of plants and inhibits central metabolic activities such as photosynthesis. The halotolerant green alga Dunaliella can adapt to hypersaline environments and is considered a model photosynthetic organism for salinity tolerance. To clarify the molecular basis for salinity tolerance, a proteomic approach has been applied for identification of salt-induced proteins in Dunaliella. Seventy-six salt-induced proteins were selected from two-dimensional gel separations of different subcellular fractions and analyzed by mass spectrometry (MS). Application of nanoelectrospray mass spectrometry, combined with sequence-similarity database-searching algorithms, MS BLAST and MultiTag, enabled identification of 80% of the salt-induced proteins. Salinity stress up-regulated key enzymes in the Calvin cycle, starch mobilization, and redox energy production; regulatory factors in protein biosynthesis and degradation; and a homolog of a bacterial Na(+)-redox transporters. The results indicate that Dunaliella responds to high salinity by enhancement of photosynthetic CO(2) assimilation and by diversion of carbon and energy resources for synthesis of glycerol, the osmotic element in Dunaliella. The ability of Dunaliella to enhance photosynthetic activity at high salinity is remarkable because, in most plants and cyanobacteria, salt stress inhibits photosynthesis. The results demonstrated the power of MS BLAST searches for the identification of proteins in organisms whose genomes are not known and paved the way for dissecting molecular mechanisms of salinity tolerance in algae and higher plants.  相似文献   

9.
Carbon metabolite feedback regulation of leaf photosynthesis and development   总被引:16,自引:0,他引:16  
Photosynthesis is regulated as a two-way process. Light regulates the expression of genes for photosynthesis and the activity of the gene products (feedforward control). Rate of end-product use down-stream of the Calvin cycle, determined largely by nutrition and temperature, also affects photosynthetic activity and photosynthetic gene expression (feedback control). Whereas feedforward control ensures efficient light use, feedback mechanisms ensure that carbon flow is balanced through the pathways that produce and consume carbon, so that inorganic phosphate is recycled and nitrogen is distributed optimally to different processes to ensure growth and survival. Actual mechanisms are sketchy and complex, but carbon to nitrogen balance rather than carbon status per se is central to understanding carbon metabolite feedback control of photosynthesis. In addition to determining the activity of the metabolic machinery, carbon metabolite feedback mechanisms also regulate photosynthesis at the leaf level through the regulation of leaf development. This review summarizes the current sketchy, but growing, knowledge of the mechanisms through which carbon metabolite feedback mechanisms regulate leaf photosynthesis.  相似文献   

10.
臭氧胁迫对植物主要生理功能的影响   总被引:9,自引:0,他引:9  
列淦文  叶龙华  薛立 《生态学报》2014,34(2):294-306
近年来,由于光化学反应的臭氧前体增加,全球植物受对流层臭氧(O3)胁迫的程度越来越严重。臭氧污染被认为是造成东欧、西欧和整个美国的大片森林衰退和枯死的主要原因。臭氧胁迫严重影响植物叶片对光能的利用,通过气孔限制和非气孔限制,导致其光合速率的降低,影响光合产物的产量。臭氧对植物的影响与植物体内代谢物质的积聚量紧密联系。臭氧胁迫引发植物的各种防御保护机制,刺激抗氧化系统,影响膜系统,改变其体内碳和矿质养分的吸收并引起它们的重新分配,诱导其基因表达的深层变化。为了适应臭氧胁迫环境,植物通过生理生化机制的调节来保证其生命活动。如细胞通过调节渗透物质的含量来保持渗透势的平衡;细胞内各种抗氧化酶活性增加,以清除自由基,避免或者减轻细胞受到伤害;改变代谢途径以保持能量储备和降低代谢速率。可见,生态环境对生物进化具有重要影响。这个观点将在臭氧胁迫对植物生理的影响中得到证实,也是生物进化论的另一种证据。综述了臭氧对光合生理、呼吸代谢、抗氧化系统、膜系统、矿质养分的吸收和分配与分子生理等主要生理功能的影响,并提出臭氧胁迫对植物生理影响的今后研究方向与未来研究热点是:(1)加强在植物个体和群落水平上臭氧胁迫对植物生理影响的研究;(2)臭氧影响下植物的基因调控和相关信号传递网络系统的机理;(3)通过分子标记、基因图谱、基因组学和转基因技术等方法研究选育适应臭氧胁迫环境的植物;(4)尽可能在接近自然条件的环境中开展研究;(5)臭氧胁迫对亚热带和热带森林及其树种主要生理功能影响的研究;(6)建立模型评估臭氧对植物的影响。  相似文献   

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