Figure 3
Plasma membrane localization of OsCPK18. Wild-type OsCPK18 and a N-terminal myristoylation mutant were transiently expressed as GFP fusion proteins in onion epidermal cells. Confocal images were taken 24 h post-bombardment. (A) Diagrams of the constructs used for particle bombardment of onion epidermal cells, wild OsCPK18-GFP and the mutant OsCPK18-GFP fusion protein in which the Gly2 was mutated to Ala (OsCPK18G2A). (B) Localization of wild OsCPK18-GFP fusion protein. Merged pictures of the green fluorescence channel with the corresponding light micrographs are shown in on the right. (C) Localization of GFP. (D) Onion cells after plasmolysis with mannitol (15 min of treatment). Light micrographs show the shrinkage of the protoplast (white arrow). (E) Treatment with mannitol renders the Hechtian strands (arrows) attaching the plasma membrane to the cell wall. (F) Onion epidermal cells expressing a mutated version of OsCPK18 with an altered myristoylation site (OsCPK18G2A-GFP). While the wild-type protein is localized to the plasma membrane, the G2A mutant protein lost its specific plasma membrane localization. Projection (B, C, D, F) and individual (E) sections are shown. Scale bars = 20 μm (B, C, D, F), 10 μm (E).