The subcellular localization of CIPK9, CBL2, and CBL3 and the interaction of CIPK9 with CBL2 and CBL3 in Arabidopsis mesophyll protoplasts. A, Transient expression of CIPK9-EGFP, CBL2-EGFP, CBL3-EGFP, and EGFP in Arabidopsis mesophyll protoplasts. B, Vacuoles were isolated after bursting of the transformed protoplasts, and the images were collected immediately. C, Analysis of the interaction between CIPK9 and CBL2 or CIPK9 and CBL3 in Arabidopsis mesophyll protoplasts by BiFC assays. D, Vacuoles were isolated after bursting of the transformed protoplasts, and the images were collected immediately. Plasmid combinations are indicated on the left. Left panels, GFP fluorescence microscopy images; middle panels, bright-field microscopy images; right panels, merge of bright-field and fluorescence microscopy images. Bars = 10 μm.