Nitric oxide mediates the fungal elicitor-induced hypericin production of Hypericum perforatum cell suspension cultures through a jasmonic-acid-dependent signal pathway.
Fungal elicitor prepared from the cell walls of Aspergillum niger induces multiple responses of Hypericum perforatum cells, including nitric oxide (NO) generation, jasmonic acid (JA) biosynthesis, and hypericin production. To determine the role of NO and JA in elicitor-induced hypericin production, we study the effects of NO scavenger 2- to 4-carboxyphenyl-4,4, 5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPITO), nitric oxide synthase inhibitor S,S'-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea, and inhibitors of the octadecanoid pathway on elicitor-induced NO generation, JA biosynthesis, and hypericin production. Pretreatment of the cells with cPITO and JA biosynthesis inhibitors suppresses not only the elicitor-induced NO generation and JA accumulation but also the elicitor-induced hypericin production, which suggests that both NO and JA are involved in elicitor-induced hypericin biosynthesis. S,S'-1,3-phenylene-bis(1,2-ethanediyl)-bis-isothiourea and cPITO inhibit both elicitor-induced NO generation and JA biosynthesis, while JA biosynthesis inhibitors do not affect the elicitor-induced NO generation, indicating that JA acts downstream of NO generation and that its biosynthesis is regulated by NO. External application of NO via its donor sodium nitroprusside induces hypericin production in the absence of fungal elicitor. Sodium-nitroprusside-induced hypericin production is blocked by JA biosynthesis inhibitors, showing that JA biosynthesis is essential for NO-induced hypericin production. The results demonstrate a causal relationship between elicitor-induced NO generation, JA biosynthesis, and hypericin production in H. perforatum cells and indicate a sequence of signaling events from NO to hypericin production, within which NO mediates the elicitor-induced hypericin biosynthesis at least partially via a JA-dependent signaling pathway.
Xu
Mao-Jun
MJ
State Key Lab of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China. maojunxu@163.com
Dong
Ju-Fang
JF
Zhu
Mu-Yuan
MY
D000873:Anthracenes; D001234:Aspergillus niger; D002478:Cells, Cultured; D003517:Cyclopentanes / Q000378:metabolism*; D005656:Fungal Proteins / Q000494:pharmacology; D020902:Hypericum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D054883:Oxylipins; D010569:Perylene / Q000031:analogs & derivatives* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000096:biosynthesis; D015398:Signal Transduction
D000873:Anthracenes; D003517:Cyclopentanes; D005656:Fungal Proteins; D054883:Oxylipins; D010937:Plant Growth Regulators; D009569:Nitric Oxide; D010569:Perylene; C011006:jasmonic acid; C004965:hypericin