title: Nitric oxide functions as a signal in ultraviolet-B-induced baicalin accumulation in Scutellaria baicalensis suspension cultures.
abstract: Stress induced by ultraviolet-B (UV-B) irradiation stimulates the accumulation of various secondary metabolites in plants. Nitric oxide (NO) serves as an important secondary messenger in UV-B stress-induced signal transduction pathways. NO can be synthesized in plants by either enzymatic catalysis or an inorganic nitrogen pathway. The effects of UV-B irradiation on the production of baicalin and the associated molecular pathways in plant cells are poorly understood. In this study, nitric oxide synthase (NOS) activity, NO release and the generation of baicalin were investigated in cell suspension cultures of Scutellaria baicalensis exposed to UV-B irradiation. UV-B irradiation significantly increased NOS activity, NO release and baicalin biosynthesis in S. baicalensis cells. Additionally, exogenous NO supplied by the NO donor, sodium nitroprusside (SNP), led to a similar increase in the baicalin content as the UV-B treatment. The NOS inhibitor, Nω-nitro-l-arginine (LNNA), and NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) partially inhibited UV-B-induced NO release and baicalin accumulation. These results suggest that NO is generated by NOS or NOS-like enzymes and plays an important role in baicalin biosynthesis as part of the defense response of S. baicalensis cells to UV-B irradiation.
authors.affiliation: School of Marine Science, Ningbo University, Ningbo 315211, Zhejiang, China. zhangjinjie@nbu.edu.cn.
authors.forename: Jin-Jie
authors.initials: JJ
authors.lastname: Zhang
authors.affiliation: Tianmu College, Zhejiang A&F University, Zhuji 311800, Zhejiang, China. lxqin@zafu.edu.cn.
authors.forename: Xue-Qin
authors.initials: XQ
authors.lastname: Li
authors.affiliation: Department of Biology, College of Life Sciences, China Jiliang University, No. 258 Xueyuan Road, Hangzhou 310018, Zhejiang, China. juville@cjlu.edu.cn.
authors.forename: Jun-Wei
authors.initials: JW
authors.lastname: Sun
authors.affiliation: Tianmu College, Zhejiang A&F University, Zhuji 311800, Zhejiang, China. shjin@zafu.edu.cn.
authors.forename: Song-Heng
authors.initials: SH
authors.lastname: Jin
mesh_terms: D001565:Benzoates / Q000494:pharmacology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D015394:Molecular Structure; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D031364:Scutellaria baicalensis / Q000166:cytology; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects*; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D001565:Benzoates; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D020030:Nitric Oxide Donors; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D009599:Nitroprusside; D019335:Nitroarginine; D009569:Nitric Oxide; C038044:baicalin; D019001:Nitric Oxide Synthase