Masami Mato

Flavonoid biosynthesis in white-flowered Sim carnations (Dianthus caryophyllus)

Abstract Analysis of flavonoid composition and gene expression of enzymes involved in anthocyanin synthesis in flowers of four acyanic and one cyanic cultivar of Sim carnation showed that the acyanic flower cultivars are divided into three types. The first includes two normal white cultivars, ‘U Conn Sim’ and ‘White Sim’; the second includes a nearly pure white cultivar, ‘Kaly’; and the third includes a nearly pure white cultivar, ‘White Mind’. ‘U Conn Sim’ and ‘White Sim’ accumulated flavonol glycosides and lacked anthocyanins. The transcription of the several genes of enzymes involved in flavonoid biosynthesis were reduced at a later flowering stage than the cyanic cultivar, especially the genes encoding dihydroflavonol 4-reductase and anthocyanidin synthase. ‘Kaly’ accumulated flavanone glycosides and a small amount of flavonol and flavone glycosides by blocking the transcription of the gene encoding flavanone 3-hydroxylase, in addition to the transcriptional reduction of the genes for flavonoid biosynthesis at a later flowering stage. Although ‘White Mind’ contains little flavonoid, the position of the block on flavonoid biosynthesis in ‘White Mind’ is not known.

Flavonol Changes in Seedlings of Vigna mungo During Growth

Summary The accumulation of three glycosides of each of kaempferol and quercetin in seedlings of Vigna mungo was demonstrated by using high performance liquid chromatography. The identity of these compounds was determined in comparison to standards by paper chromatographic and UV spectral analyses; they include kaempferol 3-O-robinobioside-7-O-rhamnoside (robinin) (K1), kaempferol 3-O-rutinoside (K2), kaempferol 7-O-rhamnoside (K3), quercetin 3-O-robinobioside-7-O-rhamnoside (Q1), quercetin 3-O-rutinoside (rutin) (Q2) and quercetin 3-O-glucoside (isoquercitrin) (Q3). K1, K2, and K3 (trace) were found in young leaves of 4 to 20-day-old seedlings, while Q1, Q2, Q3 and K1 were found in the hypocotyls and stems. At the age of 2 to 6 months, both leaves and stems produced all six flavonol glycosides.

Detection and characterization of anS-adenosyl-l-methionine: Flavonoid 7-O-methyltransferase from leaves ofPrunus x yedoensis matsum. with special reference to prunetrin formation

An enzyme,S-adenosyl-l-methionine: flavonoid 7-O-methyltransferase (F7OMT), catalyzing the transfer of the methyl group fromS-adenosyl-l-methionine (SAM) to the 7 position of sophoricoside (5, 7, 4′-trihydroxyisoflavone 4′-O-glucoside) and some of the other flavonoids, was detected in extracts from leaves ofPrunus x yedoensis, and it was partially purified (about 203-fold) by a combination of gel filtration and ion-exchange column chromatographies. F7OMT was isolated as a soluble enzyme with a pH optimun of 7.5 in K-phosphate buffer. The molecular mass of F7OMT, which had an isoelectric point at pH 4.1, was estimated by elution from a column of Sephadex G-100 to be about 36 kDa. The activity of F7OMT was stimulated by 14 mM 2-Co2+ and reagents that react with sulfhydryl groups. The apparentKm values for sophoricoside, its aglycone genistein (5, 7, 4′-trihydroxyisoflavone) and quercetin were 1.49, 2.19 and 1.89 μM, respectively. The apparentKm value for SAM as methyl donor was 2.08 mM. The specificity of F7OMT for methyl acceptors was not strict; flavonols, flavanones and flavanonols in addition to isoflavones served as methyl acceptor.An examination ofP. x yedoensis leaves during spring and autumn showed variations in the activities of F7OMT and UDP-glucose: isoflavone 4′-O-glucosyltransferase (I4′ GT). The activities of F7OMT and I4′GT increased in enlarging leaf tissues and then markedly declined when the leaves approached maturation. In autumn leaves F7OMT activity was scarcely detected, but a small peak of I4′GT activity was observed during autumnal reddening.