PROTEIN-PHOSPHORYLATION IS INDUCED IN TOBACCO CELLS BY THE ELICITOR CRYPTOGEIN

Changes in plasmalemma ion fluxes were observed when tobacco (Nicotian a tabacum) cells were treated with cryptogein, a proteinaceous elicito r from Phytophthora cryptogea. A strong alkalization of the culture me dium, accompanied by a leakage of potassium, was induced within a few minutes of treatment. These effects reached a maximum after 30 to 40 m in and lasted for several hours. This treatment also resulted in a rap id, but transient, production of activated oxygen species. All these p hysiological responses were fully sensitive to staurosporine, a known protein kinase inhibitor. Furthermore, a study of protein phosphorylat ion showed that cryptogein induced a staurosporine-sensitive phosphory lation of several polypeptides. These data suggest that phosphorylated proteins may be essential for the transduction of elicitor signals.