Arabidopsis thaliana ecotype Cvi shows an increased tolerance to photo-oxidative stress and contains a new chloroplastic copper/zinc superoxide dismutase isoenzyme

A new chloroplastic Cu/zn-su peroxide dismutase (SOD) isoenzyme was identified in Arabidopsis thaliana ecotype Cvi. Genetic analyses indicated that the new isoenzyme was encoded by a Cvi-specific allele of Csd2 that was named Csd2-2. Paraquat treatments of A. thaliana ecotypes Ler and Cvi resulted in higher levels of chloroplastic Cu/Zn-SOD activity in Cvi, suggesting that the Cvi isoenzyme has a higher stability and/or turnover rate than the Ler variant under photooxidative conditions. In addition, Cvi showed a higher tolerance to paraquat treatments. Hybrid plant populations expressing Csd2-2 also exhibited an increased tolerance, suggesting that the Cvi isoenzyme is one of the factors that contribute to a better fitness in photo-oxidative stress conditions.