Elicitor-Stimulated ion Fluxes and O2 -from the Oxidative Burst are Essential Components in Triggering Defense Gene Activation and Phytoalexin Synthesis in Parsley

• Published in: Proceedings of the National Academy of Sciences - PNAS 1997-04, Vol.94 (9), p.4800-4805
• Main Authors: Jabs, Thorsten, Tschope, Markus, Colling, Christiane, Hahlbrock, Klaus, Scheel, Dierk
• Format: Article
• Language: English
• Subjects: Biological Sciences; Cell culture techniques; Cell death; Cell membranes; Cell walls; Cultured cells; Gene activation; Genes; Ion channels; Parsley; Reactive oxygen species
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.9.4800

Fungal elicitor stimulates a multicomponent defense response in cultured parsley cells (Petroselinum crispum). Early elements of this receptor-mediated response are ion fluxes across the plasma membrane and the production of reactive oxygen species (ROS), sequentially followed by defense gene activation and phytoalexin accumulation. Omission of Ca2+from the culture medium or inhibition of elicitor-stimulated ion fluxes by ion channel blockers prevented the latter three reactions, all of which were triggered in the absence of elicitor by amphotericin B-induced ion fluxes. Inhibition of elicitor-stimulated ROS production using diphenylene iodonium blocked defense gene activation and phytoalexin accumulation. O2 -but not H2O2stimulated phytoalexin accumulation, without inducing proton fluxes. These results demonstrate a causal relationship between early and late reactions of parsley cells to the elicitor and indicate a sequence of signaling events from receptor-mediated activation of ion channels via ROS production and defense gene activation to phytoalexin synthesis. Within this sequence, O2 -rather than H2O2appears to trigger the subsequent reactions.