Abstract
GPX-like protein from the halotolerant Chlamydomonas W80 (C. W80) shows activity towards unsaturated fatty acid hydroperoxides (PUFAOOH), but towards neither H2O2 nor phospholipid hydroperoxide. Here, we generated transgenic tobacco plants expressing a GPX-like protein in the cytosol (TcGPX) or chloroplasts (TpGPX). The activities towards α-linolenic acid hydroperoxide in TpGPX and TcGPX were 32.7-42.1 and 47.5-75.3 nmol/min/mg protein, respectively, while no activity was detected in the wild-type plants (WT). The transgenic plants showed increased tolerance to oxidative stress caused by application of methylviologen (50 μM), chilling (4°C), or salinity (250 mM NaCl). Under these stress conditions, the lipid hydroperoxidation in TcGPX and TpGPX was clearly suppressed compared with that of WT. Interestingly, TpGPX lines seemed to be more tolerant compared with TcGPX lines.These results clearly indicate that a high level of GPX-like protein functions to remove PUFAOOH generated in cellular membranes under stress conditions.
