INVOLVEMENT OF A GTP-BINDING PROTEIN IN SIGNAL-TRANSDUCTION IN POTATO-TUBERS TREATED WITH THE FUNGAL ELICITOR FROM PHYTOPHTHORA-INFESTANS

Treatment of potato tuber tissues with fungal elicitor hyphal wall components (HWC) from Phytophthora infestans, the late blight fungus, caused an increase of guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S)-binding to microsomal fractions prepared from these tissues. This binding was specifically suppressed by GDP. GTPase activity also increased when the tissues were treated with HWC. GTP gamma S-binding activities responded positively when treated with HWC at 1 h compared with controls and gradually increased until 5 h. The results suggest a role for a GTP-binding protein in signal transduction following the HWC stimulus.