Crassulacean acid metabolism (CAM) plants exhibit a complex interplay between CO(2) fixation by phosphoenolpyruvate carboxylase (pepc) and ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), and carbon demand f...
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Crassulacean acid metabolism (CAM) plants exhibit a complex interplay between CO(2) fixation by phosphoenolpyruvate carboxylase (pepc) and ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), and carbon demand for CAM maintenance and growth. This study investigated the flux of carbon from pepc and direct Rubisco fixation to different leaf carbon pools and to phloem sap over the diurnal cycle. Concentrations and carbon isotope compositions of starch, soluble sugars, and organic acids were determined in leaves and phloem exudates of Kalanchoe daigremontiana Hamet et Perr., and related to CO(2) fixation by pepc and Rubisco. Three types of leaf carbon pools could be distinguished. (i) Starch and malate pools were dominant and showed a pattern of reciprocal mobilization and accumulation (85/54 and 13/48 mg C g(-1) DW, respective, at the beginning/end of phase I). The carbon isotope composition of these pools was compatible with predominant pepc fixation (delta(13)C values of -13 and -11 parts per thousand for starch and malate compared to -11 parts per thousand of pepc fixed carbon). (ii) Isotopic composition (-17 parts per thousand and -14 parts per thousand) and concentration of glucose and fructose (2 and 3 mg C g(-1) DW, respectively) were not affected by diurnal metabolism, suggesting a low turnover. (iii) Sucrose (1-3 mg C g(-1) DW), in contrast, exhibited large diurnal changes in delta(13)C values (from -17 parts per thousand in the evening to -12 parts per thousand in the morning), which were not matched by net changes in sucrose concentration. This suggests a high sucrose turnover, fed by nocturnal starch degradation and direct Rubisco fixation during the day. A detailed dissection of the carbon fixation and mobilization pattern in K. daigremontiana revealed that direct fixation of Rubisco during the light accounted for 30% of phloem sucrose, but only 15% of fixed carbon, indicating that carbon from direct Rubisco fixation was preferentially used for leaf
作者:
Pingbo ChenXia LiKai HuoXiaodong WeiChuanchao DaiInstitute of Food Crops
Jiangsu Academy of Agricultural SciencesJiangsu High Quality Rice R&D CenterNanjing BranchChina National Center for Rice ImprovementNanjing 210014China College of Life Science
Nanjing Agricultural UniversityNanjing 210095China Institute of Food CropsJiangsu Academy of Agricultural SciencesJiangsu High Quality Rice R&D CenterNanjing BranchChina National Center for Rice ImprovementNanjing 210014China jiangsu Key Laboratory for Microbes and Functional GenomicsJiangsu Engineering and Technology Research Center for Industrialization of Microbial ResourcesCollege of Life ScienceNanjing Normal UniversityNanjing 210014China
We determined the effects of exogenous nitric oxide(NO)donors and various inhibitors on photosynthesis and gene expression in transgenic rice plants(PC)overexpressing the maize C4 pepc gene,which encodes phosphoenolpy...
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We determined the effects of exogenous nitric oxide(NO)donors and various inhibitors on photosynthesis and gene expression in transgenic rice plants(PC)overexpressing the maize C4 pepc gene,which encodes phosphoenolpyruvate *** were subjected to treatments with NO donors,an NO scavenger,phospholipase inhibitors,a Ca2+chelator,a Ca2+channel inhibitor,and a peroxide inhibitor,individually and in various combinations.
1 Meathods1.1 Molecular cloning ofpepc gene Based on the core sequence obtained,RACE technique was used to amplify the pepc gene of Cyperus esculentus L..Specific reaction steps were carried out according to Clontech&...
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1 Meathods1.1 Molecular cloning ofpepc gene Based on the core sequence obtained,RACE technique was used to amplify the pepc gene of Cyperus esculentus L..Specific reaction steps were carried out according to Clontech's SMARTer 5'/3'RACE Kit1.2 Quantitative RT-PCR analysis The 40-day Cyperus esculentus *** were selected and natural light as the different treatments,relative expression ofpepc were measured in 10:00 12:00 14:00 16:00 18:00 20:00 and in
作者:
Xia LiChenggang RenInstitute of Food Crops
Jiangsu Academy of Agricultural Sciences Jiangsu High Quality Rice R&D Center Nanjing Branch of China National Center for Rice Improvement Nanjing 210014 China
Phosphoenolpymvate carboxylase(pepc) of maize, the crucial enzyme in the C4 photosynthetic pathway, has been successfully transformed into C3 crop rice and is highly *** transgenic rice's photosynthetic rate h...
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Phosphoenolpymvate carboxylase(pepc) of maize, the crucial enzyme in the C4 photosynthetic pathway, has been successfully transformed into C3 crop rice and is highly *** transgenic rice's photosynthetic rate has also been ***, the improvement of C3 crops' photosynthetic efficiency by transforming C4-photosynthetic specialty has attracted more and more *** this discovery, an increasing amount of research on rice breeding showed that pepc transgenic rice also has tolerance to oxidative stress, especially from high intensity light, and it was clearly related to the *** the important functional molecule of oxidative stress, there are many ways in which hydrogen peroxide may be generated, as it plays an important role inside plant *** paper mainly investigates the relationship between the photosynthetic specialty of C4-pepc transgenic rice (PC) and hydrogen peroxide signaling.
pepc, PPKD and NADP-ME are the most important enzymes in the C_4 pathway of photosynthesis which have introduced into C_3 plants to increase efficiency of photosynthesis. In this paper the strategy of introduction of ...
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ISBN:
(纸本)9781457718823
pepc, PPKD and NADP-ME are the most important enzymes in the C_4 pathway of photosynthesis which have introduced into C_3 plants to increase efficiency of photosynthesis. In this paper the strategy of introduction of the intact C_4-specific gene into C_3 plants would be expected to lead to high level and cell-expression of C_4 enzymes in mesophyll cells. By contrast, over expression of enzymes specific of bundle sheath cells, conventional techniques with gene constructs containing a strong promoter fused to a cDNA were effective.
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