Differential responses of the scavenging systems for reactive oxygen species (ROS) and reactive carbonyl species (RCS) to UV-B irradiation in Arabidopsis thaliana and its high altitude perennial relative Arabis alpina.

The present work aimed to compare antioxidant response and lipid peroxide detoxification capacity of an arctic-alpine species Arabis alpina to its close relative model species Arabidopsis thaliana under acute short duration (3 h and 6 h) UV-B stress (4.6 and 8.2 W/m2). After 3 and 6 h exposure to UV-B, A. alpina showed lower lipid peroxidation and H2O2 accumulation when compared to A. thaliana. Moreover, Fv/Fm value of A. thaliana dropped to 0.70, while A. alpina dropped to 0.75 indicating better protection of PSII in this species. For elucidation of the antioxidant response, activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR) and dehydroascorbate reductase (DHAR) were measured. SOD induction with 6 h of UV-B was more prominent in A. alpina. Also, A. alpina had higher chloroplastic FeSOD activity when compared to A. thaliana. APX activity was also significantly induced in A. alpina, while its activity decreased at 3 h or did not change at 6 h in A. thaliana. A. alpina was able to maintain constant CAT activity, but drastic decreases were observed in A. thaliana at both time points. Moreover, A. alpina was able to maintain or induce aldehyde dehydrogenase (ALDH), alkenal reductases (AERs) and glutathione-S-transferases (GST) activity, while an opposite trend was observed in A. thaliana. These findings indicate that A. alpina was able to maintain/induce its antioxidant defence and lipid peroxide detoxification conferring better protection against UV-B.