Two tobacco genes induced by infection, elicitor and salicylic acid encode glucosyltransferases acting on phenylpropanoids and benzoic acid derivatives, including salicylic acid

Abstract

Two tobacco genes (TOGT) with homology to glucosyltransferase genes known to be induced by salicylic acid (SA) also responded rapidly to a fungal elicitor or to an avirulent pathogen. SA, although an efficient inducer, was shown not to be essential in the signal transduction pathway regulating TOGT gene expression during the resistance response. Recombinant TOGT proteins produced in Escherichia coli exhibited low, but significant, glucosyltransferase activity towards SA, but very high activity towards hydroxycoumarins and hydroxycinnamic acids, with glucose esters being the predominant products. These results point to a possible important function in defense of these glucosyltransferases in conjugating aromatic metabolites prior to their transport and cross-linking to the cell wall.z 1998 Federation of European Biochemical Societies.

Cloning and heterologous expression of cDNAs encoding flavonoid glucosyltransferases from Dianthus caryophyllus

“…Samsun NN (Fraissinet-Tachet et al 1998). Vogt et al (2002) showed that GT enzymatic activity prepared from cultured cells of D. bellidiformis catalyzed various flavonoid glucosides.…”

Cloning and characterization of a glucosyltransferase that reacts on 7-hydroxyl group of flavonol and 3-hydroxyl group of coumarin from tobacco cells

“…The expression of some GTase genes can be induced by plant hormones, such as salicylic acid [16,17,22], auxin [16,22] or jasmonate [19], and many of them show a broad substrate specificity. Since NTGT2 also shows a broad substrate specificity, RT-PCR was performed to determine the expression pattern of NtGT2 mRNA in plant-hormone-treated tobacco cells.…”

“…The reported members of this GTase family are baicalein 7-O-glucosyltransferase, B5GT, salicylate-inducible GTases (IEGT [16]) and their homologues (TOGT [17]) from tobacco. B5GT was reported to be able to catalyze the glucosylation of 4'-OH or 7-OH of quercetin, but the activity against 7-OH was 10-fold lower than that against 4'-OH [15].…”

Purification and characterization of UDP-glucose: hydroxycoumarin 7-O-glucosyltransferase, with broad substrate specificity from tobacco cultured cells

“…(D. Horvath, personal communication). It was also reported that the products of homologues genes glucosylate several kinds of phenylpropanoids, but flavonoids were not considered as possible substrates [29]. Scopoletin is known as one of the phytoalexins that can be induced by fungal infection or by treatment with plant hormones in tobacco.…”