Lack of cytochrome c in Arabidopsis decreases stability of Complex IV and modifies redox metabolism without affecting Complexes I and III

► Knock-out of cytochrome c causes embryo lethality in plants. ► Plants with low cytochrome c levels have increased alternative respiration. ► Cytochrome c may participate in the assembly/stabilization of Complex IV in plants. ► Mutants show reduced ROS levels and induction of genes encoding antioxidant enzymes. ► A small amount of cytochrome c is enough to support normal ascorbic acid synthesis.