Author(s): Felix G, Grosskopf DG, Regenass M, Boller T
Abstract Share this page
Abstract Plant cells have an acute sense for pathogen-derived chemical stimuli, so-called elicitors, which induce the plant's defense response. To investigate the molecular basis of chemosensory transduction, elicitor-treated tomato cells were labeled with 1-min pulses of [32P] phosphate. This technique revealed drastic changes in protein phosphorylation in vivo within minutes of stimulation. The protein kinase inhibitors K-252a and staurosporine completely prevented these elicitor-induced changes in protein phosphorylation. They also blocked two early biochemical responses to elicitors, extracellular alkalinization and biosynthesis of ethylene. The ability of K-252a, staurosporine, and benzoylated staurosporine derivatives to inhibit elicitor responses in vivo correlated with their ability to inhibit tomato microsomal protein kinase in vitro. When K-252a was given to elicited cells 1 min after the phosphate, the radioactivity in certain newly labeled phosphoprotein bands disappeared again within minutes. This correlated with an arrest of alkalinization within minutes when K-252a was applied in midcourse of elicitation. These data show that phosphorylation of protein substrates by K-252a-sensitive protein kinases is essential for transduction of elicitor signals in plant cells and that continuous phosphorylation of these proteins is required to maintain the elicited state.
This article was published in Proc Natl Acad Sci U S A
and referenced in Journal of Biodiversity, Bioprospecting and Development