Abstract Two cDNA clones encoding cytosolic and plastidic Cu Zn -superoxide dismutases (SOD, EC 18.104.22.168), SAcSODcy and SAcSODpl respectively, were isolated from a goldenrod ( Solidago altissima) cDNA library. The cDNA clones comprised a complete open reading frame and their deduced amino acid sequences were highly homologous with those of previously identified cytosolic or plastidic Cu Zn -SSOD from other plant species. Northern blot analysis revealed a higher mRNA level of plastidic Cu Zn -SOD gene ( SodCp) in leaves and lower in roots than that of cytosolic Cu Zn -SOD gene ( SodCc). In leaves of rosette plants, the transcripts of SodCp gene accumulated during light exposure for 3 days, but not those of SodCc. On the other hand, the mRNA levels of both genes were increased in response to oxidative stress imposed by paraquat. However, different expression patterns were observed in the two genes: the expression level of SodCc gene was gradually increased up to 4 h after paraquat treatment, while that of SodCp was rapidly increased for 2 h but was diminished at 4 h after treatment. These findings demonstrate that different regulation mechanisms are involved in the expression of SodCc and SodCp genes against oxidative stress in S. altissima.