title: Nitric oxide regulates shikonin formation in suspension-cultured Onosma paniculatum cells.
abstract: Endogenously occurring nitric oxide (NO) is involved in the regulation of shikonin formation in Onosma paniculatum cells. NO generated after cells were inoculated into shikonin production medium reached the highest level after 2 d of culture, which was 16 times that at the beginning of the experiment, and maintained a high level for 6 d. A nitric oxide synthase (NOS) inhibitor, N(omega)-nitro-L-arginine (L-NNA), and a nitrate reductase (NR) inhibitor, sodium azide (SoA), consistent with their inhibition of NO biosynthesis, decreased shikonin formation significantly. This reduction could be alleviated or even abolished by exogenous NO supplied by sodium nitroprusside (SNP), suggesting that the inhibition of NO biosynthesis resulted in decreased shikonin formation. However, when endogenous NO biosynthesis was up-regulated by the elicitor from Rhizoctonia cerealis, shikonin production was enhanced further, showing a dependence on the elicitor-induced NO burst. Real-time PCR analysis showed that NO could significantly up-regulate the expression of PAL, PGT and HMGR, which encode key enzymes involved in shikonin biosynthesis. These results demonstrated that NO plays a critical role in shikonin formation in O. paniculatum cells.
authors.affiliation: Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, PR China.
authors.forename: Shu-Jing
authors.initials: SJ
authors.lastname: Wu
authors.forename: Jin-Liang
authors.initials: JL
authors.lastname: Qi
authors.forename: Wen-Ju
authors.initials: WJ
authors.lastname: Zhang
authors.forename: Shao-Hua
authors.initials: SH
authors.lastname: Liu
authors.forename: Feng-Hui
authors.initials: FH
authors.lastname: Xiao
authors.forename: Ming-Sheng
authors.initials: MS
authors.lastname: Zhang
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Xu
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Zhao
authors.forename: Ming-Wang
authors.initials: MW
authors.lastname: Shi
authors.forename: Yan-Jun
authors.initials: YJ
authors.lastname: Pang
authors.forename: Heng-Guan
authors.initials: HG
authors.lastname: Shen
authors.forename: Yong-Hua
authors.initials: YH
authors.lastname: Yang
mesh_terms: D028082:Boraginaceae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media; D004578:Electron Spin Resonance Spectroscopy; D018506:Gene Expression Regulation, Plant; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009285:Naphthoquinones / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000494:pharmacology; D018749:RNA, Plant / Q000378:metabolism
chemical_list: D003470:Culture Media; D009285:Naphthoquinones; D018749:RNA, Plant; D009569:Nitric Oxide; C016101:shikonin; D019331:NG-Nitroarginine Methyl Ester