NAD(P)H oxidases were detected in suspension cultured cells of ginseng (Panax ginseng C. A. Meyer). The activities of these enzymes were induced by an elicitor (Cle) extracted from cell walls of Col-letotrichum lagera...NAD(P)H oxidases were detected in suspension cultured cells of ginseng (Panax ginseng C. A. Meyer). The activities of these enzymes were induced by an elicitor (Cle) extracted from cell walls of Col-letotrichum lagerarium. In addition, Cle induced an oxidative burst and enhanced the synthesis of saponin, activity of phenylalanine ammonialyase (PAL) , accumulation of chalcone synthase (CHS) and the transcription of a hydroxyproline-rich glycoprotein gene ( hrgp ) . Pre-treatments with DPI and quinacrine (two inhibitors of mammalian neutrophil plasma membrane NADPH oxidase) for 30 min prior to Cle addition blocked the NAD(P)H oxidase activity induced by Cle. These inhibitors also inhibited the release of H2C2, the synthesis of saponin, PAL activity and CHS accumulation. Our data revealed homology between plasma membrane NAD(P)H oxidases of mammalian neutrophil cells and ginseng suspension cells. They also indicated that deactivated NAD(P)H oxidases catalysed the release of H2O2 and that H2O2 was functioning as a second messenger stimulating PAL activity, saponin synthesis and hrgp transcription. Elevations of Ca2 + and protein phos-phorylation/dephosphorylation were required for this defense process. We propose that NAD(P)H oxidases mediate the processes of Cle-induced defense responses in ginseng suspensions, and postulate the existence of a signalling cascade including extracellular Cle stimulation, activation of plasma membrane NAD(P)H oxidases, release of H2O2, and the intracellular responses of metabolism and gene transcription in ginseng suspension cells.展开更多
文摘NAD(P)H oxidases were detected in suspension cultured cells of ginseng (Panax ginseng C. A. Meyer). The activities of these enzymes were induced by an elicitor (Cle) extracted from cell walls of Col-letotrichum lagerarium. In addition, Cle induced an oxidative burst and enhanced the synthesis of saponin, activity of phenylalanine ammonialyase (PAL) , accumulation of chalcone synthase (CHS) and the transcription of a hydroxyproline-rich glycoprotein gene ( hrgp ) . Pre-treatments with DPI and quinacrine (two inhibitors of mammalian neutrophil plasma membrane NADPH oxidase) for 30 min prior to Cle addition blocked the NAD(P)H oxidase activity induced by Cle. These inhibitors also inhibited the release of H2C2, the synthesis of saponin, PAL activity and CHS accumulation. Our data revealed homology between plasma membrane NAD(P)H oxidases of mammalian neutrophil cells and ginseng suspension cells. They also indicated that deactivated NAD(P)H oxidases catalysed the release of H2O2 and that H2O2 was functioning as a second messenger stimulating PAL activity, saponin synthesis and hrgp transcription. Elevations of Ca2 + and protein phos-phorylation/dephosphorylation were required for this defense process. We propose that NAD(P)H oxidases mediate the processes of Cle-induced defense responses in ginseng suspensions, and postulate the existence of a signalling cascade including extracellular Cle stimulation, activation of plasma membrane NAD(P)H oxidases, release of H2O2, and the intracellular responses of metabolism and gene transcription in ginseng suspension cells.
