PMF proteins mediate mitochondrial fusion in Arabidopsis

mutants show reduced mitochondrial volume and severe fusion defects under hypoxic stress. We further show that PMF1's cytoplasmic, intrinsically disordered N terminus undergoes liquid-liquid phase separation, a property necessary and sufficient to promote mitochondria fusion in vivo. These results reveal PMF-mediated protein condensation as a kingdom-specific mechanism regulating mitochondrial dynamics in plant cells.