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Phosphoinositide-specific phospholipase C (PI-PLC) cleaves, in a Ca²⁺-dependent manner, phosphatidylinositol-4,5-bisphosphate (PI-4,5-P₂) into diacylglycerol (DAG) and inositol triphosphate (IP₃). PI-PLCs are multidomain proteins that are structurally related to the PI-PLCζs, the simplest animal PI-PLCs. Like these animal counterparts, they are only composed of EF-hand, X/Y and C2 domains. However, plant PI-PLCs do not have a conventional EF-hand domain since they are often truncated, while some PI-PLCs have no EF-hand domain at all. Despite this simple structure, plant PI-PLCs are involved in many essential plant processes, either associated with development or in response to environmental stresses. The action of PI-PLCs relies on the mediators they produce. In plants, IP₃ does not seem to be the sole active soluble molecule. Inositol pentakisphosphate (IP₅) and inositol hexakisphosphate (IP₆ …