P2K1 P2K2 Coordinate Early, Structure-Specific Mechanical Adaptations to Osmotic and Cell Wall Stress in Arabidopsis Roots

The cell wall and plasma membrane (PM) form the interface between a plant cell and its environment yet how their mechanical properties change in response to stress is poorly understood. Here we investigate how the mechanical properties of the cell wall, plasma membrane, and vacuole change in vivo in Arabidopsis thaliana roots in response to hyperosmotic stress and cell wall damage (CWD) using a solvatochromic dye, molecular rotors, and Brillouin microscopy. We observe initially dynamic changes in mechanical properties of the PM that are sensitive to both hyperosmotic stress and CWD, while the cell wall changes are limited and the vacuole adapts only after several hours. In the p2k1 p2k2 double mutant, lacking receptors for extracellular ATP perception, sorbitol-induced effects on PM mechanostasis and early isoxaben-induced increases in PM order are lost. Our results indicate that P2K1 and P2K2 are required to modulate adaptive changes in mechanical properties of the PM induced by hyperosmotic stress and CWD.