Involvement of nitric oxide in elicitor-induced defense responses and secondary metabolism of Taxus chinensis cells.
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.
Wang
Jian Wen
JW
Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Wu
Jian Yong
JY
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
D011522:Protons; D009599:Nitroprusside; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010650:Phenylalanine Ammonia-Lyase; D017239:Paclitaxel; D011188:Potassium