IRON AND COPPER NUTRITION-DEPENDENT CHANGES IN PROTEIN EXPRESSION IN A TOMATO WILD-TYPE AND THE NICOTIANAMINE-FREE MUTANT CHLORONERVA

The nicotianamine-deficient mutant chloronerva resembles phenotypicall y an Fe-deficient plant despite the high accumulation of Fe in the lea ves, whereas it suffers from Cu deficiency in the shoot. Two-dimension al electrophoretic separation of proteins from root tips and leaves of wild-type Lycopersicon esculentum Mill. cv Bonner Beste and the mutan t grown with and without Fe showed a number of consistent differences. In root tips of the Fe-deficient wild type and the Fe-sufficient as w ell as the Fe-deficient mutant, the expression of glyceraldehyde-3-pho sphate dehydrogenase, formate dehydrogenase, and ascorbate peroxidase was increased. In leaves of the Fe-sufficient and -deficient mutant, C u-containing chloroplastic and cytosolic superoxide dismutase (Cu-Zn) and plastocyanin (Cu) were nearly absent. This low plastocyanin conten t could be restored by supplying Cu via the xylem, but the superoxide dismutase levels could not be increased by this treatment. The differe nces in the protein patterns between wild type and mutant indicate tha t the apparent Fe deficiency of mutant plants led to an increase in en zymes involved in anaerobic metabolism as well as enzymes involved in stress defense. The biosynthesis of plastocyanin was diminished in mut ant leaves, but it was differentially induced by increased Cu content.