Chloroplastic NADPH-dependent alkenal/one oxidoreductase contributes to the detoxification of reactive carbonyls produced under oxidative stress

► Chloroplastic alkenal/one oxidoreductase (AOR) catalyzes the reduction of α,β-unsaturated bond in reactive carbonyls (RCs). ► AOR-knock out Arabidopsis line (aor) was used to examine endogenous effect of RCs. ► aor mutants were susceptible to methyl viologen treatment accelerating reactive oxygen species production from photosystem. ► RCs produced under oxidative stress inhibited photosystem. ► AOR contributes to the detoxification of stromal RCs produced under oxidative stress in vivo. Lipid peroxide-derived reactive carbonyls (RCs) can cause serious damage to plant functions. A chloroplastic NADPH-dependent alkenal/one oxidoreductase (AOR) detoxifies RCs, but its physiological significance remains unknown. In this study, we investigated the biological impacts of AOR using an AOR-knock out Arabidopsis line (aor). Methyl viologen treatment, mainly to enhance photosystem (PS) I-originated reactive oxygen species (ROS) production, caused more severe damage to aor than wild type (Col-0). In contrast, the high light treatment used to enhance PSII-originated ROS production resulted in no difference in PSII damage between Col-0 and aor. In conclusion, AOR can contribute to detoxify stromal RCs produced under oxidative stress.