Isoflavone And Pterocarpan Malonylglucosides And ß - L,3 - Glucan - And Chitin-Hydrolases Are Vacuolar Constituents In Chickpea (Cicer Arietinum L.)

Mackenbrock, Ulrike; Vogelsang, R.; Barz, Wolfgang

doi:10.1515/znc-1992-11-1206

Cited by 34 publications

(19 citation statements)

References 18 publications

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“…This ABCtype transporter also seems to be specific to isoflavones as transport substrates because all isoflavones tested inhibited genistein transport in the competition assay, whereas flavanone and flavonol do not seem to be recognized by the transporter protein (Table II). In plants, flavonoids often accumulate as the glucoside forms and the transport of flavonoid glucosides into vacuoles has also been reported (Mackenbrock et al, 1992;Klein et al, 1996;Frangne et al, 2002), but the transport of flavonoid aglycones at the plant plasma membrane has not been biochemically characterized thus far, except for this study. .…”

Section: Discussionmentioning

confidence: 94%

Involvement of a Soybean ATP-Binding Cassette-Type Transporter in the Secretion of Genistein, a Signal Flavonoid in Legume-Rhizobium Symbiosis

2007

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Legume plants have an ability to fix atmospheric nitrogen into nutrients via symbiosis with soil microbes. As the initial event of the symbiosis, legume plants secrete flavonoids into the rhizosphere to attract rhizobia. Secretion of flavonoids is indispensable for the establishment of symbiotic nitrogen fixation, but almost nothing is known about the membrane transport mechanism of flavonoid secretion from legume root cells. In this study, we performed biochemical analyses to characterize the transport mechanism of flavonoid secretion using soybean (Glycine max) in which genistein is a signal flavonoid. Plasma membrane vesicles prepared from soybean roots showed clear transport activity of genistein in an ATP-dependent manner. This transport activity was inhibited by sodium orthovanadate, a typical inhibitor of ATP-binding cassette (ABC) transporters, but was hardly affected by various ionophores, such as gramicidin D, nigericin, or valinomycin, suggesting involvement of an ABC transporter in the secretion of flavonoids from soybean roots. The K m and V max values of this transport were calculated to be 158 mM and 322 pmol mg protein 21 min 21 , respectively. Competition experiments using various flavonoids of both aglycone and glucoside varieties suggested that this ABC-type transporter recognizes genistein and daidzein, another signaling compound in soybean root exudates, as well as other isoflavonoid aglycones as its substrates. Transport activity was constitutive regardless of the availability of nitrogen nutrition. This is, to our knowledge, the first biochemical characterization of the membrane transport of flavonoid secretion from roots.Plant root exudates secreted into the soil mediate complex interactions between soil-born microorganisms and plants. These interactions occur in the small region around the plant roots, which is called the rhizosphere, where plants protect root tissues from attack by bacteria and fungi and symbiotic interactions with rhizobia and arbuscular mycorrhiza are also involved in a cooperative context. Examples of root exudates responsible for the protective actions include cyclic hydroxamic acids, such as 2,4-dihydroxy-7-methoxy-1, 4-benzoxazin-3-one and the naphthoquinone-derivative shikonin [5,8-dihydroxy-2-(1-hydroxy-4-methylpent-3-en-1-yl)-1,4-naphthoquinone], which were reported in wheat (Triticum aestivum) and Lithospermum erythrorhizon, respectively (Niemeyer, 1988;Brigham et al., 1999). The well-known phenomenon called allelopathy, in which organic compounds in the root exudates or secondary metabolites produced in the aerial part of the plant cause deleterious effects on neighboring plants, thus suppressing the growth of other plants, is an example of interactions between plants in the rhizosphere (Weir et al., 2004). In contrast to the negative interactions between plants and other organisms, positive interactions between plants and microbes also occur in the rhizosphere. Flavonoids in root exudates of legume plants activate nod gene expression of rhizobia (Peters et a...

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Section: Discussionmentioning

confidence: 94%

Involvement of a Soybean ATP-Binding Cassette-Type Transporter in the Secretion of Genistein, a Signal Flavonoid in Legume-Rhizobium Symbiosis

2007

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“…Based on either confocal microscopy or computational prediction, G2, G3, and G4 are localized to either vacuole or cytosol. The isoflavone conjugates of chickpea cell suspension cultures are vacuolar localized (37), and these compounds were found in the soluble fraction (cytoplasmic plus vacuolar contents) in Medicago. Cell fractionation studies suggested that chickpea isoflavone glucosidase activity was primarily cytoplasmic, whereas the malonylesterase activity responsible for the initial degradation of isoflavone-7-O-glucoside-6ЈЈ-malonate (38) was associated with the vacuolar membrane (37).…”

Section: Discussionmentioning

confidence: 99%

Different mechanisms for phytoalexin induction by pathogen and wound signals in Medicago truncatula

Naoumkina

Farag

Sumner

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

171

157

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Cell suspensions of the model legume Medicago truncatula accumulated the isoflavonoid phytoalexin medicarpin in response to yeast elicitor or methyl jasmonate (MJ), accompanied by decreased levels of isoflavone glycosides in MJ-treated cells. DNA microarray analysis revealed rapid, massive induction of early (iso)flavonoid pathway gene transcripts in response to yeast elicitor, but not MJ, and differential induction by the two elicitors of sets of genes encoding transcription factors, ABC transporters, and ␤-glucosidases. In contrast, both elicitors induced genes encoding enzymes for conversion of the isoflavone formononetin to medicarpin. Four MJ-induced ␤-glucosidases were expressed as recombinant enzymes in yeast, and three were active with isoflavone glucosides. The most highly induced ␤-glucosidase was nuclear localized and preferred flavones to isoflavones. The results indicate that the genetic and biochemical mechanisms underlying accumulation of medicarpin differ depending on the nature of the stimulus and suggest a role for MJ as a signal for rapid hydrolysis of preformed, conjugated intermediates for antimicrobial biosynthesis during wound responses.glucosidase ͉ methyl jasmonate ͉ phytoanticipin ͉ cell culture ͉ elicitation

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“…Nevertheless, isoflavone glycosides are hydrolyzed to their aglycones by lactobacilli, Bacteroides and Bifidobacteria in the intestinal flora, and by lactase phlorizin hydrolase in the small intestinal brush border cells (43). Glycosylation may be a favorable trait for engineered isoflavonoid nutraceuticals, as it results in their storage in the vacuole (44), away from further potential metabolism.…”

Section: Ifs Expression Affects Flavonol and Anthocyanin Biosynthesismentioning

confidence: 99%

Bottlenecks for metabolic engineering of isoflavone glycoconjugates inArabidopsis

Liu

Blount²,

Steele³

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

167

147

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In view of their perceived chemopreventive activities against hormone-dependent cancers, cardiovascular disease, and postmenopausal ailments, there is considerable interest in engineering plants to contain isoflavone phytoestrogens. However, attempts to date have only resulted in low levels of isoflavone accumulation in non-legumes. Introducing soybean isoflavone synthase (IFS) into Arabidopsis thaliana leads to accumulation of low levels of genistein glycosides. Leaves of wild-type A. thaliana contain high levels of similar conjugates of the flavonols quercetin and kaempferol, which could be increased by threefold on introduction of an alfalfa chalcone isomerase transgene. Levels of genistein were not increased by expressing both IFS and alfalfa chalcone isomerase, but levels of flavonol conjugates were reduced to a greater extent than could be accounted for by flux into isoflavone. Introduction of IFS into the tt6͞tt3 double mutant blocked in flavonol, and anthocyanin synthesis resulted in high levels of genistein. The bottleneck for constitutive isoflavone production in Arabidopsis is, therefore, competition for flavanone between IFS and endogenous flavonol synthesis, and the flavonol pathway is reciprocally but disproportionately affected by IFS.flavonol ͉ phytoestrogen ͉ antioxidant ͉ metabolic engineering ͉ transgenic plants

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Isoflavone And Pterocarpan Malonylglucosides And ß - L,3 - Glucan - And Chitin-Hydrolases Are Vacuolar Constituents In Chickpea (Cicer Arietinum L.)

Cited by 34 publications

References 18 publications

Involvement of a Soybean ATP-Binding Cassette-Type Transporter in the Secretion of Genistein, a Signal Flavonoid in Legume-Rhizobium Symbiosis

Involvement of a Soybean ATP-Binding Cassette-Type Transporter in the Secretion of Genistein, a Signal Flavonoid in Legume-Rhizobium Symbiosis

Different mechanisms for phytoalexin induction by pathogen and wound signals in Medicago truncatula

Bottlenecks for metabolic engineering of isoflavone glycoconjugates inArabidopsis

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