Involvement of nitric oxide in elicitor-induced defense responses and secondary metabolism of Taxus chinensis cells |
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Authors: | Jian Wen Wang Jian Yong Wu |
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Institution: | Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. |
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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. |
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Keywords: | Nitric oxide Fungal elicitor Taxus cells Oxidative burst K+/H+ fluxes Paclitaxel |
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