O2- from elicitor-induced oxidative burst is necessary for triggering phenylalanine ammonia-lyase activation and catharanthine synthesis in Catharanthus roseus cell cultures 

 -  Enzyme and Microbial Technology, 36(2-3), p.280-284, 2005 .
<br/><br/> Elicitor, derived from the cell walls of Aspergillus niger, induced rapid generation of reactive oxygen intermediates (ROI), including superoxide anion (O2-)and hydrogen peroxide (H2O2), sequentially followed by phenylalanine ammonia-lyase (PAL)activation and catharanthine biosynthesis in Catharanthus roseus suspension cells. The elicitor-induced PAL activation and catharanthine biosynthesis were blocked by NAD(P)H oxidase inhibitor, diphenylene iodonium (DPI). O2- generated by the reaction of xanthine/xanthine oxidase (X/XO)triggered PAL activation and catharanthine biosynthesis of C. roseus cells in the absence of elicitor and reversed the inhibitory effect of DPI on elicitor-induced PAL activation and catharanthine biosynthesis. External application of H2O2 and catalase had no effect on PAL activity and catharanthine contents of C. roseus cells. The results demonstrated a causal relationship between elicitor-induced oxidative burst and PAL activation in C. roseus suspension cells and suggested a sequence of signaling events from ROI production to PAL activation and catharanthine synthesis. Within this sequence, O2- rather than H2O2 appeared to trigger the subsequent reactions 
<br/><br/><label>Subjects--Topical Terms: </label><br/>SUPEROXIDE ANIONS<br/>H2O2<br/>ELICITOR<br/>CATHARANTHUS ROSEUS CELLS<br/>CATHARANTHINE<br/>PAL