Involvement of cAMP signaling in elicitor-induced phytoalexin accumulation in Cupressus lusitanica cell cultures
Author for correspondence: Kokki Sakai Tel: +81 92 6422988 Fax: +81 92 6422988 Email: email@example.com
- • An increasing body of evidence on plant electrophysiology, biochemistry, and molecular biology shows that cAMP exists in higher plants and plays a role in several physiological processes by affecting potassium (K+) or calcium (Ca2+) fluxes. Our study here reports that cAMP is involved in elicitor-induced accumulation of a phytoalexin, β-thujaplicin, in Cupressus lusitanica cell cultures.
- • Treatment of C. lusitanica cultured cells with cAMP or its analogues stimulated β-thujaplicin accumulation. Cholera toxin and forskolin, activators of adenylyl cyclase, also stimulated β-thujaplicin accumulation. Enzyme immunoassay showed that after elicitor treatment, cAMP level in the elicited cells quickly increased to about three- to five-fold over the control. Cholera toxin and forskolin also stimulated cAMP accumulation in the absence of elicitor.
- • However, K+ and Ca2+ channel blockers inhibited the β-thujaplicin accumulation induced by cAMP analogues, suggesting that the cAMP-stimulated β-thujaplicin accumulation may involve Ca2+ and K+ fluxes. Several ionophores mimicked cAMP induction of β-thujaplicin accumulation.
- • Cross-talk between cAMP treatment and the ethylene signaling pathway was also observed to work in the cell cultures via Ca2+ signaling. The study also indicates an involvement of protein kinase cascades in cAMP signaling processes, leading to both phytoalexin and ethylene production.