Stimulation of barley plasmalemma H+-ATPase by phytotoxic peptides from the fungal pathogen Rhynchosporium secalis

Abstract

A small family of necrosis-inducing peptides has been identified as virulence factors of Rhynchosporium secalis, a fungal pathogen of barley (Hordeum vulgare L.) Two members of this family, NIP1 and NIP3, were found to stimulate the phosphohydrolyzing activity of the Mg2+-dependent, K+-stimulated H+-ATPase of plasma membrane vesicles isolated from barley leaves by partitioning in an aqueous two-phase system. Stimulation of enzyme activity was saturated by 10 to 15 μM fungal protein. Another member of the peptide family, NIP2, did not affect the enzyme, indicating that it has a different mode of action.