Dynamics and cell-to-cell transmission of wound-induced calcium waves in plants

Plants can perceive a variety of external stimuli and respond to these with local and systemic signals that coordinate the response across tissues, organs and the whole plant body. When wounded, plant cells respond with an increase in cytoplasmic calcium levels that can propagate cell-to-cell locally and systemically in a wave-like manner. Plant bodies are multicellular networks of cells embedded in the common environment of the cell wall and symplastically connected via plasmodesmata. Previous works have observed that plasmodesmata play a key role in cell-to-cell transmission of calcium waves upon wounding. However, the mechanism by which this occurs have not been studied yet. Here, I developed new experimental and computational methods that allow the study of the dynamics of cell-to-cell signal propagation with high spatial-temporal resolution. This revealed that the local calcium response to wounding has at least three temporally distinct phases (a local burst, a propagating wave and a late diffuse calcium increase) differing in their dynamics and underlying mechanisms. Further, the cell-to-cell propagation of local and systemic wound-induced calcium waves is independent from TPC1, RBOHD, RBOHF and symplastic connectivity. In addition, the local and systemic non-vascular calcium waves are dependent on GLR3.3 and display propagation dynamics typical of a diffusion-driven process, while the systemic vascular waves display velocity and dynamics compatible with xylem bulk flow. Together, the data presented in this work provide new insights on the mechanisms of generation and cell-to-cell transmission of calcium waves upon-wounding and create new leads and opportunities for further investigations