Enhanced activity of galactono-1,4-lactone dehydrogenase and ascorbate-glutathione cycle in mitochondria from complex III deficient Arabidopsis

► Ppr40-1 Arabidopsis can be characterized by elevated level of ROS and use of Asc. ► The activity of the Asc biosynthetic enzyme GLDH is elevated in ppr40-1 mitochondria. ► Increased activity of Asc-GSH cycle can also be observed in the mutant mitochondria. ► Lower Asc and Asc plus DHA contents were detected in ppr40-1 tissue and mitochondria. ► The observed compensatory mechanism is not fully successful.