Nitric oxide regulates shikonin formation in suspension-cultured Onosma paniculatum cells.
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.
Wu
Shu-Jing
SJ
Institute of Plant Molecular Biology, State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, PR China.
Qi
Jin-Liang
JL
Zhang
Wen-Ju
WJ
Liu
Shao-Hua
SH
Xiao
Feng-Hui
FH
Zhang
Ming-Sheng
MS
Xu
Guo-Hua
GH
Zhao
Wei-Guo
WG
Shi
Ming-Wang
MW
Pang
Yan-Jun
YJ
Shen
Heng-Guan
HG
Yang
Yong-Hua
YH
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
D003470:Culture Media; D009285:Naphthoquinones; D018749:RNA, Plant; D009569:Nitric Oxide; C016101:shikonin; D019331:NG-Nitroarginine Methyl Ester