Plants metabolism

The literature of alkaloids can conveniently be divided into five sections, dealing with (1) the occurrence and distribution of these substances in plants (2) biogenesis, or the methods by which alkaloids are produced in the course of plant metabolism (3) analysis, ranging from the commercial and industrial estimation of particular alkaloids to the separation, purification and description of the individual components of the natural mixture of alkaloids, which normally occurs in plants (4) determination of structure and (5) pharmacological action. 

The first step in this study has involved experiments which synthesize alkaloids in vitro under quasi-cellular conditions, using reactions which can proceed in the living cell and compounds which actually occur in the cell or which are supposed to be intermediates in the plant metabolism. Such synthesesaredesignatedassyntheses under physiological conditions. ... 

In Europe the situation is radically different. Isotopic variations at the bottom end of the food web, brought about by differences in plant metabolism (C3, versus C4 and CAM), and origin of the fixed COj, (causing a systematic discrepancy between terrestrial and marine ecosystems) are generally absent. This leads to relatively small variations in ratios at the beginning of... 

DELLAPENNA D (2001) Plant metabolic engineering . Plant Physiol, 125, 160-63. 

Possible exposure to pesticide-derived N,-nitroso compounds depends on environmental processes that influence formation, movement, and degradation of the compounds. Although laboratory studies have shown the feasibility of environmental nitrosamine formation, there has been little evidence that it is an important process. Nitrosamines vary greatly in their environmental stabilities, but all seem to be susceptible to one or more modes of decomposition including photolysis, microbiological degradation, and plant metabolism. 

Plant use is less biotechnologically advanced and fundamentally more complex. The first generation of plant metabolic engineering met with mixed success and produced unanticipated results — problems that are not necessarily restricted to manipulation of carotenogenesis. The reason is that predictive metabolic engineering relies on the establishment of both needed tools and an information infrastructure... 

Broun, P. and Somerville, C., Progress in plant metabolic engineering, Proc. Natl. Acad. Sci. USA 98, 8925, 2001. 

Sandmann, G., Rbmer, S., and Eraser, P.D., Understanding carotenoid metabolism as a necessity for genetic engineering of crop plants, Metabol. Eng. 8, 291, 2006. DellaPenna, D., Plant metabolic engineering. Plant Physiol. 125, 160, 2001. Wurtzel, E.T. and Grotewold, E., Plant metabolic engineering, in Encyclopedia of... 

Ohlrogge, J., Plant metabolic engineering are we ready for phase two Curr. Opin. Plant Biol. 2, 121, 1999. 

Morgan, J.A. and Rhodes, D., Mathematical modeling of plant metabolic pathways, Metabol. Eng. 4, 80, 2002. 

Eoyer, C.H., DellaPenna, D., and Van Der Straeten, D., A new era in plant metabolism research reveals a bright future for bio-fortification and human nutrition. Physiol. Plantarum 126, 289, 2006. 

Sandermann H (1994) Higher plant metabolism of xenobiotics the green liver concept. Pharmacogenetics 4 225-241. 

This chapter focuses on the effects of humic substances present at the rhizo-sphere on plant growth and nutrient uptake. The main structural features of humic substances, their nutritional function, and the capacity to interact with plant metabolism are also presented. 

Plant metabolism studies will provide information on the absorption, translocation, dissipation and degradation of the agrochemical. This information defines the residual analytes of regulatory concern that could include either the parent compound or metabolites in the field crops. Plant metabolism studies should be conducted with at least three crop representatives of three different crop groups listed in Table 1. One of the major objectives is to determine the comparative metabolism of the agrochemicals between animals and plants among different plant species. MAFF approves metabolism studies that are conducted in foreign countries, which should be operated under the certified GLP system. 

The toxic effects of selected plant analytes will be assessed by comparison with the toxicides of similar metabolites found in animal metabolism studies. The amount of the analytes reported in the plant metabolism study is one of the important factors used to establish the residue definition. 

E) coumarins, (F) quinones, (G) flavonoids, (H) tannins, (I) alkaloids, (J) terpenoids and steroids and (K) miscellaneous and unknowns. Although many of these compounds are secondary products of plant metabolism, several are also degradation products which occur in the presence of microbial enzymes. 

Factors Affecting Allelochemical Production or Release and their Modes of Action. This area of research should prove fruitful for the plant physiologists and biochemists who are interested in regulation of plant metabolism. Studies to date have been limited to only a few compounds. 

The absorption of the ether bis(2-fluoroethoxy)methane from the soil and its translocation in plants in a concentration sufficient to kill insects is a recent discovery heretofore observed only in some selenium compounds and in the insecticidal esters of some polyphosphoric acids (4) Whether this property is shared by other organofluorine compounds will doubtless be determined for the purpose of studying plant metabolism and of evaluating any practical application. 

De Kok LJ, Maas FM, Stulen I, et al. 1988. Sulfur containing air pollutants and their effects on plant metabolism. Commission of European Communities 11244 620-625... 

Conventionally, central and special metabolic pathways are distinguished. Central pathways are common to the decomposition and synthesis of major macromolecules. Actually, they are much alike in all representatives of the living world. Special cycles are characteristic of the synthesis and decomposition of individual monomers, macromolecules, cofactors, etc. Special cycles are extremely diversified, especially in the plant kingdom. For this reason, the plant metabolism is conventionally classified into primary and secondary metabolisms. The primary metabolism includes the classical processes of synthesis and deeradation of major macromolecules (proteins, carbohydrates, lipids, nucleic acids, etc.), while the secondary metabolism ensuing from the primary one includes the conversions of special biomolecules (for example, alkaloids, terpenes, etc.) that perform regulatory or other functions, or simply are metabolic end byproducts. 

Keywords. Polyhydroxyalkanoates, Polyhydroxybutyrate, Polyester, Transgenic plants, Metabolic engineering... 

Fig. 1. Modification of plant metabolic pathways for the synthesis of poly(3HB) and poly(3HB-co-3HV). The pathways created or enhanced by the expression of transgenes are highlighted in bold, while endogenous plant pathways are in plain letters. The various transgenes expressed in plants are indicated in italics. The ilvA gene encodes a threonine deaminase from E. coli. The phaARe, phaBRe, and phaCRe genes encode a 3-ketothiolase, an aceto-acetyl-CoA reductase, and a PHA synthase from R. eutropha, respectively. The btkBRe gene encodes a second 3-ketothiolase isolated from R. eutropha which shows high affinity for both propionyl-CoA and acetyl-CoA [40]. PDC refers to the endogenous plant pyruvate dehydrogenase complex...

Fig. 4. Modification of plant metabolic pathways for the synthesis of poly(3HAMCL) in peroxisomes. The pathways created or enhanced by the expression of transgenes (P. aeruginosa PHA synthase and C. lanceolata decanoyl-ACP thioesterase) and of mutant alleles of plant fatty acid desaturase genes are highlighted by bold arrows and the enzymes involved underlined...

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