Subcellular localization of flavonoid synthesizing enzymes in Pisum, Phaseolus, Brassica and Spinacia cultivars

Hrazdina, G.; Alscher-Herman, Ruth; Kish, Valerie M.

doi:10.1016/0031-9422(80)80173-7

Cited by 27 publications

(13 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This soluble enzyme had an apparent mol wt of 42,000 D and an isoelectric point of 5.1. Its general properties were similar to those of other reported flavonoid glucosyltransferases with respect to pH optimum, mol wt, requirement for SH groups, inhibition by divalent cations and by either of the reaction products (8,13,14,17,18,20,24). Plant Physiol.…”

Section: Discussionsupporting

confidence: 54%

Purification and Properties of Flavonol-Ring B Glucosyltransferase from Chrysosplenium americanum

Bajaj¹,

Luca²,

Khouri³

et al. 1983

Plant Physiol.

View full text Add to dashboard Cite

A novel glucosyltransferase which catalyzed the transfer of glucose from UDP-glucose to positions 2' and 5' of partially methylated flavonols was isolated from the shoots of Chrysosplenium americanum Schwein ex Hooker. It was purified 225-fold by ammonium sulfate precipitation and successive chromatography on Sephadex G-100, hydroxyapatite, and polybuffer ion exchanger. This glucosyltransferase appeared to be a single polypeptide with an apparent molecular weight of 42,000 daltons, pH optimum of 7.5 to 8.0, and an isoelectric point of 5.1. It had low but similar Km values for the 2' and 5' positions of flavonol substrates and the cosubstrate UDP-glucose and was inhibited by both reaction products, the glucosides formed, and UDP.Glucosyltransferase activity was independent of divalent cations, was not inhibited by EDTA, but showed requirement for SH groups. The differential effect on enzyme activity of metal ions, especially cupric ion, and various SH group reagents seemed to indicate the involvement of two active sites in the glucosylation reaction; the site specific for 2' activity being more susceptible than that of the 5' activity. The substrate specificity expressed by this glucosyltransferase and the requirement of at least two para-oriented B-ring substituents (at 2' and 5') for activity support this view.

show abstract

Section: Discussionsupporting

confidence: 54%

Purification and Properties of Flavonol-Ring B Glucosyltransferase from Chrysosplenium americanum

Bajaj¹,

Luca²,

Khouri³

et al. 1983

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Chloroplasts have also been suggested as being sites of phenylpropanoid and flavonoid metabolism, but the evidence is contradictory. Various flavonoids, certain cinnamic acid derivatives (9) and some phenylpropanoid and flavonoid biosynthetic enzymes were reported to occur in isolated plastids (14). Other reports conclude that plastids lack key enzymes ofthese pathways (9,22 (Figs.…”

mentioning

confidence: 99%

Endoplasmic Reticulum as a Site of Phenylpropanoid and Flavonoid Metabolism in Hippeastrum

Wagner¹,

Hrazdina²

1984

Plant Physiol.

View full text Add to dashboard Cite

ABSTRACTwith ER vesicles has not been ruled out (22). It is possible that ER-chloroplast associations which exist in vivo (2) may be maintained in certain chloroplast preparations.In earlier studies with Hippeastrum petal protoplasts (8), we found that 5 to 15% ofthe activities of key phenylpropanoid and flavonoid pathway enzymes was associated with a particultate subcellular fraction which was enriched in ER membranes. There is no published evidence to support the presence on or in the tonoplast of enzymes ofthese pathways or ofenzymes leading to other secondary products. No evidence was found to suggest the occurrence of UDPG-flavonoid glucosyltransferase (an enzyme near the end of the flavonoid biosynthetic sequence) on or in isolated tonoplast of Hippeastrum (24).To expand our understanding of the intracellular location of secondary product formation in plants, we fractionated petal homogenate-derived membranes on sucrose density gradients and utilized the EDTA shift method to demonstrate that various key enzymes ofphenylpropanoid and flavonoid metabolism are, at least in part, ER-bound.Biochemical and ultastructural studies have provided evidence to support the contention that phenylpropanoid and flavonoid biosynthesis occur on the ER (5,11, 22, 25). A number of investigators have shown that certain enzymes ofthese metabolic pathways are associated with microsomal membranes (11,20, 22) and Czichi and Kindl (3) demonstrated coupling between PAL2 and C4-H in microsomal preparations of potato and cucumber. Compelling micrographs of Douglas Fir callus cells suggest that 'tannin'-containing vesicles can arise from dilated regions of the rough RER, (16), and other ultrastructural studies (25) suggest that ER is the site of tannin synthesis in several tannin accumulating plants. Chloroplasts have also been suggested as being sites of phenylpropanoid and flavonoid metabolism, but the evidence is contradictory. Various flavonoids, certain cinnamic acid derivatives (9) and some phenylpropanoid and flavonoid biosynthetic enzymes were reported to occur in isolated plastids (14). Other reports conclude that plastids lack key enzymes ofthese pathways (9, 22). The possibility that plastid preparations which showed enzyme activities were contaminated ' The investigation reported in this paper ) is in connection with a project ofthe Kentucky Agricultural Experiment Station and is published with approval of the Director.

show abstract

“…There is evidence to suggest that synthesis of some flavonoids is closely associated with chloroplast activity McClure 1976a, 1976b) and if this also applies to biflavones their presence in the middle leaf fraction would not be surprising. However, there is evidence to indicate that other flavonoids are synthesized and stored entirely within the epidermis (McClure 1975;Hrazdina et al 1980). It is also possible that the trace of biflavones detected in the middle leaf extract is simply due to contamination by epidermal tissue.…”

Section: Discussionmentioning

confidence: 99%

Localization of the Biflavonoid Fraction in Plant Leaves, With Special Reference to Agathis robusta (C. Moore Ex F. Muell.) F.m. Bail

Gadek¹,

Quinn²,

Ashford³

1984

Aust. J. Bot.

View full text Add to dashboard Cite

Aluminium chloride-induced fluorescence was used to localize biflavonoids in fresh leaf sections of Agathis robusta. This method indicates that the biflavonoids are confined to the outer periclinal wall and anticlinal walls of the epidermal cells. This was confirmed by extraction and chromatographic analysis of epidermal peels, cuticular scrapings and middle leaf tissue fractions.A survey of representatives of the Psilotales, and of all orders of the gymnosperms using aluminium chloride-induced fluorescence, indicates that localization of biflavones in the cuticle is a general feature of biflavonoid-containing plants. Members of the Pinaceae and Gnetales, in which biflavonoids have not been found, show no such fluorescence in the cuticle. The possible functional roles of biflavonoid accumulation are discussed. It is postulated that biflavones serve a protective role against invasion of the leaf by microorganisms and/or attack by leaf-eating insects.Leaves of Agathis robusta were particularly suitable material in which to localize the biflavonoid fraction. Previous studies o n the leaves of this and several other species of the genus Agathis (Khan et al. 1972;Varshney et al. 1973) indicated that biflavonoids constitute by far the major proportion of the flavonoid fraction. Furthermore, unlike the scale-leaves of many conifers, the broad dorsiventral leaves of Agathis species are relatively easily separable into epidermal and mesophyll fractions, allowing confirmation of observations by t.1.c. analysis of extracts from these fractions. For these reasons the study concentrates o n Agathis robusta. However, a brief survey of the aluminium chlorideinduced fluorescence i n representatives of all orders of gymnosperms, as well as the Psilotales, is also included. Materials and MethodsUnless otherwise stated, all studies were carried out on mature leaves of specimens cultivated in the grounds of the University of New South Wales: voucher specimens have been lodged with UNSW.

show abstract

Subcellular localization of flavonoid synthesizing enzymes in Pisum, Phaseolus, Brassica and Spinacia cultivars

Cited by 27 publications

References 22 publications

Purification and Properties of Flavonol-Ring B Glucosyltransferase from Chrysosplenium americanum

Purification and Properties of Flavonol-Ring B Glucosyltransferase from Chrysosplenium americanum

Endoplasmic Reticulum as a Site of Phenylpropanoid and Flavonoid Metabolism in Hippeastrum

Localization of the Biflavonoid Fraction in Plant Leaves, With Special Reference to Agathis robusta (C. Moore Ex F. Muell.) F.m. Bail

Contact Info

Product

Resources

About