Plant metabolic networks

R. Rios Estepa and B. M. Lange, Experimental and mathematical approaches to modeling plant metabolic networks. Phytochemistry 68(16 18), 2351 2374(2007). 

R. G. Ratcliffe and Y. Shachar Hill, Measuring multiple fluxes through plant metabolic networks. Plant J. 45, 490 511 (2006). 

Schwender, J. Ohlrogge, J. Shachar-Hill, Y. Understanding flux in plant metabolic networks. Curr. Opin. Plant Biol. 2004, 7 (3), 309-317. 

R 411 N.J. Kruger, R.G. Ratcliffe and A. Roscher, Quantitative Approaches for Analysing Fluxes through Plant Metabolic Networks Using NMR and Stable Isotope Fabelling , Phytochem.Rev., 2003, 2,17... 

Formate metabolism is the most obscure sector of the plant C network, and the one where the genome has yielded the most surprises.3 Plants have formate pools that are important sources of Ci units,24"27 and plants also have formate dehydrogenase activity.28 31 However, the origin of formate is not clear. It may come from non-enzymatic decarboxylation of glyoxylate in leaves in the light,27 32 but this cannot be... 

The cytochrome P450 responsible for the oxidation of (S)-N-methylcoclaurine to (S)-3 -hydroxy-N-methylcocluarine has been overexpressed in opium poppy plants, and morphinan alkaloid production in the latex is increased subsequently to 4.5 times the level in wild-type plants (58). Additionally, suppression of this enzyme resulted in a decrease in morphinan alkaloids to 16% of the wild-type level. Notably, analysis of a variety of biosynthetic gene transcript levels in these experiments supports the hypothesis that this P450 enzyme plays a regulatory role in the biosynthesis of benzylisoquinoline alkaloids. Collectively, these studies highlight that the complex metabolic networks found in plants are not redirected easily or predictably in all cases. 

Peters RJ. Uncovering the complex metabolic network underlying diterpenoid phytoalexin biosynthesis in rice and other cereal crop plants. Phytochemistry 2006 67 2307-2317. 

Weckwerth W, Loureiro ME, Wenzel K, Fiehn O. Differential metabolic networks unravel the effects of silent plant phenotypes. 

Gulati J, Baldwin IT, Gaquerel E. The roots of plant defenses Integrative multivariate analyses uncover dynamic behaviors of gene and metabolic networks of roots elicited by leaf herbivores. Plant J 2014 77(6) 880-92. 

Delineation of biosynthesis is usually carried out by different approaches e.g., feeding of presumptive precursors labeled by radioactive or stable isotopes. As described in this review, cell suspension cultures of higher plants opened the door to a methodology for the isolation of single biosynthetic enzymes. Then the role of each participating enzyme elucidated can give evidence for entire metabolic sequences, pathways or even metabolic networks. But these approaches are invasive and might not always reflect the in vivo situation. 

Bottcher C, Westphal L, Schmotz C, Prade E, Scheel D, Glawischnig E (2009) The multifunctional enzyme CYP71B15 Phytoalexin Deficients) converts cysteine-indole-3-acetonitrile to camalexin in the indole-3-acetonitrile metabolic network of Arabidopsis thaliana. Plant Cell 21 1830-1845... 

Therefore, further progress in better understanding of the metabolic pathways and our ability to manipulate gene expression, in genetically modified plants, can be envisaged. Success of this approach depends upon the possibility to change the host metabolism and will depend primarily on a far more sophisticated knowledge of plant metabolism, especially the nuances of intercoimected cellular networks. 

Behre J, Wilhelm T, von Kamp A, Ruppin E, Schuster S (2008) Stmctuial robustness of metabolic networks with respect to multiple knockouts. J Theor Biol 252 433M41 Bell SL, Palsson BO (2005) Expa a program for calculating extreme pathways in biochemical reaction networks. Bioinformatics 21 1739-1740 Beurton-Aimar M, Beauvoit B, Monier A, Vallee F Dieuaide-Noubhani M, Colombie S (2011) Comparison between elementary flux modes analysis and 13c-metabolic fluxes measured in bacterial and plant cells. BMC Syst Biol 5 95... 

Fig. 5 Metabolic networks. Gene expression levels are correlated with the appearance of natural product production. This correlation provides clues as to which genes of the plant are involved in natural product biosynthesis...

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