Immunocytochemical localization of plant secondary metabolites and the enzymes involved in their biosynthesis

Ibrahim, Ragai K.

doi:10.1002/pca.2800010201

Cited by 9 publications

(4 citation statements)

References 89 publications

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“…Polyclonal antibodies are a better choice over monoclonal antibodies for immunohistochemistry since they are able to detect more than one epitope in the antigen. Small changes in the structure of the compound of interest due to fixation protocols usually will not affect binding affinity, and they react with structurally related compounds compared to the compound being localized (Ibrahim 1990;Ferreira et al 1998). …”

Section: Introductionmentioning

confidence: 99%

Immunohistochemical localization of caffeine in young Camellia sinensis (L.) O. Kuntze (tea) leaves

Breda

Merwe

Robbertse

et al. 2012

Planta

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Section: Introductionmentioning

confidence: 99%

Immunohistochemical localization of caffeine in young Camellia sinensis (L.) O. Kuntze (tea) leaves

Breda

Merwe

Robbertse

et al. 2012

Planta

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“…Antibodies raised against the major polymethylated flavonol glucosides of Chrysosplemium americanum detected these compounds in the cell wall of epidermal cells, the plasmalemma, the periplasm and associated vesicles (Ibrahim et al, 1987 ;Ibrahim, 1990) . In accordance with further evidence given below, it is tempting to speculate that the polymethylated flavonol glucosides are loaded into vesicles at their site of synthesis on a membrane-associated multienzyme complex from where they are secreted in flavonoid-containing vesicles towards the plasmalemma without passing the Golgi (Ibrahim, 1990 ;Latchinian-Sadek and Ibrahim, 1991) . Metabolites found in root exudates actively orchestrate plant interactions with the rhizosphere including symbiotic, pathogenic and allelopathic interaction Bais et al, 2004 ;Weisskopf et al, 2006) while the mechanisms involved in secretion of rhizosphere compounds are not well understood.…”

Section: Non-vacuolar Transportmentioning

confidence: 99%

Handling Dangerous Molecules: Transport and Compartmentation of Plant Natural Products

Klein

Roos

2009

Plant-Derived Natural Products

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The plant cell faces a dilemma: secondary products provide a multitude of defence and signalling functions, but their biosynthesis poses a severe burden, as it competes for energy sources and building blocks and may generate toxic products. Thus, evolution of recent secondary metabolites is not only driven by their advantageous functions but also selects for strict control mechanisms including the integration of biosynthesis into the cellular ultrastructure. In order to minimize the risk of self-intoxication, secondary products are usually targeted into compartments of low metabolic activity, notably the vacuole and the extracellular space. This is most obvious for phenolic substances but also for alkaloids, the best studied plant toxins. Compartmentation on a cellular or subcellular level is also instrumental in plants synthesizing preformed defence substances such as cyanogenic glycosides in order to assure that the active toxins are only liberated in case of an attack. Biosynthetic pathways and regulatory elements are wellestablished at least for some natural compound classes such as the flavonoids. In contrast, our knowledge of transport steps behind the subcellular distribution of these substances is just scratching the surface.This chapter provides an overview on transport processes involved in secondary metabolite compartmentation that is concentrated at the best known areas of flavonoid and alkaloid production. Starting from 'classical' data of secondary metabolite transport we characterize the actually known transporters -which mainly belong to the A TP-B inding C assette (ABC) or M ultidrug a nd T oxic E xtrusion (MATE) superfamilies -and their specific functioning in cells and tissues as analyzed by modern experimental techniques. The 'transporter' hypothesis is confronted with 'vesicle transport' models of subcellular trafficking. Although it appears premature to find common ground between these alternative models, the discovery of novel cellular functions of secondary metabolites facilitates our understanding of an intimate interplay between biosynthetic steps, transmembrane 11A.E. Osbourn and V. Lanzotti (eds.), Plant-derived Natural Products, 229

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“…We also demonstrated that root nodules from mature lupin plants accumulate prenylated derivatives of both genistein and 2′-hydroxygenistein, with the predominance of 2′hydroxylupalbigenin. Immunogold localization using monospecific polyclonal IgGs (Ibrahim 1990), revealed an association of 2′-hydroxylupalbigenin with the establishment of early symbiotic structures, as well as with the bacteroids themselves. The discrete location of the diprenylisoflavone label in specialized cytoplasmic organelles suggests that its compartmentalization within the wall is mediated by membrane vesicles (Grandmaison and Ibrahim 1995).…”

Section: Other Isoflavone-related Contributionsmentioning

confidence: 99%

A forty-year journey in plant research: original contributions to flavonoid biochemistry

Ibrahim¹

2005

Can. J. Bot.

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This review highlights original contributions by the author to the field of flavonoid biochemistry during his research career of more than four decades. These include elucidation of novel aspects of some of the common enzymatic reactions involved in the later steps of flavonoid biosynthesis, with emphasis on methyltransferases, glucosyltransferases, sulfotransferases, and an oxoglutarate-dependent dioxygenase, as well as cloning, and inferences about phylogenetic relationships, of the genes encoding some of these enzymes. The three-dimensional structure of a flavonol O-methyltransferase was studied through homology-based modeling, using a caffeic acid O-methyltransferase as a template, to explain their strict substrate preferences. In addition, the biological significance of enzymatic prenylation of isoflavones, as well as their role as phytoanticipins and inducers of nodulation genes, are emphasized. Finally, the potential application of knowledge about the genes encoding these enzyme reactions is discussed in terms of improving plant productivity and survival, modification of flavonoid profiles, and the search for new compounds with pharmaceutical and (or) nutraceutical value.Key words: flavonoid enzymology, metabolite localization, gene cloning, 3-D structure, phylogeny.

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Immunocytochemical localization of plant secondary metabolites and the enzymes involved in their biosynthesis

Cited by 9 publications

References 89 publications

Immunohistochemical localization of caffeine in young Camellia sinensis (L.) O. Kuntze (tea) leaves

Immunohistochemical localization of caffeine in young Camellia sinensis (L.) O. Kuntze (tea) leaves

Handling Dangerous Molecules: Transport and Compartmentation of Plant Natural Products

A forty-year journey in plant research: original contributions to flavonoid biochemistry

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