Induction of tolerance to oxidative stress in the green alga, Chlamydomonas reinhardtii, by abscisic acid

The effect of abscisic acid (ABA) on the tolerance to oxidative stress in a freshwater green alga, Chlamydomonas reinhardtii , was investigated. Exogenously added ABA enhanced the growth of this alga, which was observed under continuous illumination but not in the dark. The cells treated with ABA for 24 h showed tolerance to oxidative stress caused by exposure to paraquat or hydrogen peroxide. In the ABA-treated cells, the activities of two antioxidant enzymes, catalase (CAT) and ascorbate peroxidase (APX), were significantly higher than those in the untreated control. The result suggests that ABA plays a role in the enhancement of tolerance to oxidative stress by increasing the activity of antioxidant enzymes.