Studies on elicitor recognition and signal transduction in plant defence
1993
Renelt, A. | Colling, C. | Hahlbrock, K. | Nurnberger, T. | Parker, J.E. | Sacks, W.R. | Scheel, D.
Parsley (Petroselinum crispum) leaves develop a typical non-host resistance response to infection with spores from the soybean pathogen, Phytophthora megasperma f. sp. glycinea. Cultured parsley cells and protoplasts express most components of this complex resistance reaction upon treatment with elicitor preparations from the fungus. One elicitor-active component of this preparation is an extracellular 42 kDa glycoprotein which appears to bind specifically to target site(s) on the parsley plasma membrane, thereby initiating a transmembrane signalling process which leads to transient activation of plant defence genes. The signal transduction chain involves changes in the permeability of the plasma membrane to Ca2+, H+, Cl-, and K+; Ca2+ - dependent protein phosphorylation and or dephosphorylation and perhaps Ca2+ - release from internal stores by inositol 1,4,5-trisphosphate. Although cyclic AMP as well as heterotrimeric GTP-binding proteins appear to be present in parsley cells, no evidence has been obtained for their involvement in elicitor signal transduction. Many of these experiments required permeabilization of parsley protoplasts which was accomplished by electroporation under conditions that allowed introduction of low molecular weight compounds into the cytosol without altering elicitor responsiveness and viability.
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