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Florian A.,Max Planck Institute For Molekular Pflanzenphysiologie | Araujo W.L.,Federal University of Vicosa | Fernie A.R.,Max Planck Institute For Molekular Pflanzenphysiologie
Plant Biology | Year: 2013

Photorespiration, one of the cornerstone pathways of primary metabolism, allows plant growth in a high oxygen-containing environment. While the oxygenase reaction of Rubisco directly influences photosynthesis per se, several other processes are also affected by photorespiration, including nitrogen assimilation, respiration, amino acid metabolism, 1-C metabolism and redox metabolism, cumulating to impose a severe impact across multiple signalling pathways. Accordingly, although the plant photorespiratory cycle is complex and highly compartmentalised, little is currently known about the participating transport proteins, and relatively few of them have been properly identified. Despite its centrality, uniqueness, and mystery, the biochemistry of photorespiration has historically been quite poorly understood, in part because at least some of its enzymes and intermediates tend to be labile and of low abundance. Fortunately, the integration of molecular and genetic approaches with biochemical ones, such as metabolite profiling, is now driving rapid advances in knowledge of the key metabolic roles and connections of the enzymes and genes of the photorespiratory pathway. While these experiments have revealed a surprising complexity in the response and established connections between photorespiration and other metabolic pathways, the mechanisms behind the observed responses have still to be fully elucidated. Here we review recent progress into photorespiration and its interaction with other metabolic processes, paying particular attention to data emanating from metabolic profiling studies. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands. Source


Araujo W.L.,Federal University of Vicosa | Martins A.O.,Federal University of Vicosa | Fernie A.R.,Max Planck Institute For Molekular Pflanzenphysiologie | Tohge T.,Max Planck Institute For Molekular Pflanzenphysiologie
Frontiers in Plant Science | Year: 2014

The tricarboxylic acid (TCA) cycle intermediate 2-oxoglutarate (2-OG) is used as an obligatory substrate in a range of oxidative reactions catalyzed by 2-OG-dependent dioxygenases.These enzymes are widespread in nature being involved in several important biochemical processes. We have recently demonstrated that tomato plants in which the TCA cycle enzyme 2-OG dehydrogenase (2-ODD) was antisense inhibited were characterized by early senescence and modified fruit ripening associated with differences in the levels of bioactive gibberellin (GA). Accordingly, there is now compelling evidence that theTCA cycle plays an important role in modulating the rate of flux from 2-OG to amino acid metabolism. Here we discuss recent advances in the biochemistry and molecular biology of 2-OG metabolism occurring in different biological systems indicating the importance of 2-OG and 2-OG dependent dioxygenases not only in glucosinolate, flavonoid and alkaloid metabolism but also in GA and amino acid metabolism. We additionally summarize recent findings regarding the impactofmodificationof2-OG metabolismonbiosynthetic pathways involving 2-ODDs. © 2014 Araújo, Martins, Fernie and Tohge. Source


Araujo W.L.,Max Planck Institute For Molekular Pflanzenphysiologie | Araujo W.L.,Federal University of Vicosa | Tohge T.,Max Planck Institute For Molekular Pflanzenphysiologie | Osorio S.,Max Planck Institute For Molekular Pflanzenphysiologie | And 8 more authors.
Plant Cell | Year: 2012

Transgenic tomato (Solanum lycopersicum) plants expressing a fragment of the gene encoding the E1 subunit of the 2-oxoglutarate dehydrogenase complex in the antisense orientation and exhibiting substantial reductions in the activity of this enzyme exhibit a considerably reduced rate of respiration. They were, however, characterized by largely unaltered photosynthetic rates and fruit yields but restricted leaf, stem, and root growth. These lines displayed markedly altered metabolic profiles, including changes in tricarboxylic acid cycle intermediates and in the majority of the amino acids but unaltered pyridine nucleotide content both in leaves and during the progression of fruit ripening. Moreover, they displayed a generally accelerated development exhibiting early flowering, accelerated fruit ripening, and a markedly earlier onset of leaf senescence. In addition, transcript and selective hormone profiling of gibberellins and abscisic acid revealed changes only in the former coupled to changes in transcripts encoding enzymes of gibberellin biosynthesis. The data obtained are discussed in the context of the importance of this enzyme in both photosynthetic and respiratory metabolism as well as in programs of plant development connected to carbon-nitrogen interactions. © 2012 American Society of Plant Biologists.All rights reserved. Source

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