title: Plant Defense Response to Fungal Pathogens (Activation of Host-Plasma Membrane H+-ATPase by Elicitor-Induced Enzyme Dephosphorylation).
abstract: Elicitor preparations containing the avr5 gene products from race 4 of Cladosporium fulvum and tomato (Lycopersicon esculentum L.) cells near isogenic for the resistance gene Cf5 were used to investigate events following the treatment of host plasma membranes with elicitor. A 4-fold increase in H+-ATPase activity, coincident with the acidification of the extracellular medium, was detected immediately after elicitor treatment. The elicitor-induced stimulation of the plasma membrane H+-ATPase was inhibited by okadaic acid but not by staurosporine, suggesting that protein dephosphorylation was required for increased H+-ATPase activity. This observation was confirmed by [gamma]-32P labeling and immunodetection of the plasma membrane H+-ATPase. Effects of guanidine nucleotide analogs and mastoparan on the ATPase activity suggested the role of GTP-binding proteins in mediating the putative elicitor-receptor binding, resulting in activation of a phosphatase(s), which in turn stimulates the plasma membrane H+-ATPase by dephosphorylation.
authors.affiliation: Centre for Plant Biotechnology and Department of Botany, University of Toronto, Toronto, Ontario, M5S 3B2 Canada.
authors.forename: R.
authors.initials: R
authors.lastname: Vera-Estrella
authors.forename: B. J.
authors.initials: BJ
authors.lastname: Barkla
authors.forename: V. J.
authors.initials: VJ
authors.lastname: Higgins
authors.forename: E.
authors.initials: E
authors.lastname: Blumwald