title: Involvement of nitric oxide in elicitor-induced defense responses and secondary metabolism of Taxus chinensis cells.
abstract: This work was to characterize the generation of nitric oxide (NO) in Taxus chinensis cells induced by a fungal elicitor extracted from Fusarium oxysporum mycelium and the signal role of NO in the elicitation of plant defense responses and secondary metabolite accumulation. The fungal elicitor at 10-100 microg/ml (carbohydrate equivalent) induced a rapid and dose-dependent NO production in the Taxus cell culture, which exhibited a biphasic time course, reaching the first plateau within 1 h and the second within 12 h of elicitor treatment. The NO donor sodium nitroprusside potentiated elicitor-induced H2O2 production and cell death but had little influence on elicitor-induced membrane K+ efflux and H+ influx (medium alkalinization). NO inhibitors Nomega-nitro-L-arginine and 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide partially blocked the elicitor-induced H2O2 production and membrane ion fluxes. Moreover, the NO inhibitors suppressed elicitor-induced activation of phenylalanine ammonium-lyase and accumulation of diterpenoid taxanes (paclitaxel and baccatin III). These results suggest that NO plays a signal role in the elicitor-induced responses and secondary metabolism activities in the Taxus cells.
authors.affiliation: Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Jian Wen
authors.initials: JW
authors.lastname: Wang
authors.forename: Jian Yong
authors.initials: JY
authors.lastname: Wu
mesh_terms: D016923:Cell Death; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D005670:Fusarium / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000378:metabolism; D008564:Membrane Potentials; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000502:physiology; D009599:Nitroprusside; D017239:Paclitaxel / Q000096:biosynthesis; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011522:Protons; D016897:Respiratory Burst; D020946:Taxus / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors
chemical_list: D011522:Protons; D009599:Nitroprusside; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010650:Phenylalanine Ammonia-Lyase; D017239:Paclitaxel; D011188:Potassium