Hypersensitive Death of Potato Cells:PiPE, an elicitor of Phytophthora infestans Induced SdCDPK Signaling in the Defense Reaction

Abstract

In the presence of Ca²⁺, the kinase activity of the plasma membrane of potato is stimulated by an elicitor (PiPE) of Phytophthora infestans. Ca²⁺-dependent,CDPKs, the ser/thre kinases were isolated from potato. We isolated two CDPK cDNAs (SdCDPK1 and SdCDPK2) from cv. Rishiri. These CDPK transcripts are elevated after PiPE treatment. Recombinant kinases encoded by SdCDPK1 and SdCDPK2 were prepared to investigate the role of CDPKs in HR. We developed a new method for assaying autophosphorylation by titer plates and found that autophosphorylation of SdCDPK1- and SdCDPK2-his fusions were stimulated by the Pi suppressor of HR. We also found that smGFP-SdCDPK1 is localized to the plasma membrane. These data suggest that SdCDPK1 may play an important role in the PiPE-induced signaling cascade in the plasma membrane leading to HR. We also suggest that SdCDPK1 mediate signaling cascades of the suppressors against HR during compatible interactions between host and Pi.