2003 Volume 93 Pages 141-153
We have been studying SOD isozymes in bryophytes, considered as the most primitive land plants, and reported that the chloroplastic SOD isozymes were different between the moss Barbula unguiculata and the liverwort Marchantia paleacea var. diptera, suggesting that the isozyme patterns reflect phylogenetic relationships among land plants (Yamahara et al., 1999a). Here we describe another physiological difference between the moss and the liverwort in the expressional regulation of chloroplastic Fe-SOD by Cu. In the moss, which has two isozymes, Fe-SOD and CuZn-SOD, in its chloroplasts, Fe-SOD activity was present in the cells cultured in 0 μM Cu but little activity at concentrations above 1 μM, whereas CuZn-SOD activities were observed at concentrations higher than 0.1 μM but little activity at 0 μM. In the liverwort, which has only Fe-SOD in its chloroplasts, the Fe-SOD activity is not influenced by Cu. Analysis of cDNA clones of both chloroplastic Fe-SOD and CuZn-SOD of the moss and a chloroplastic Fe-SOD of the liverwort revealed that they are typical chloroplastic SODs very comparable to those of phanerogams. Cu presence decreases the accumulation of gene transcripts for Fe-SOD, but increases that for CuZn-SOD in the moss, whereas it produces little effect on the gene for Fe-SOD in the liverwort. The phylogenetic implication of the results is discussed in relation to the evolution of Cu-mediated transcriptional regulation of chloroplastic Fe-SOD in land plants.