TRANSLOCATION OF COPPER AND OTHER MICRONUTRIENTS IN TOMATO PLANTS (LYCOPERSICON-ESCULENTUM MILL) - NICOTIANAMINE-STIMULATED COPPER TRANSPORT IN THE XYLEM

The influence of the endogenous micronutrient chelator, nicotianamine (NA), and of Cu nutrition on the distribution of Cu, Fe, Mn, Zn, and N A was investigated in eight different shoot organs, roots, and in xyle m exudates of the NA-containing tomato wild type Lycopersicon esculent um Mill. cv. Bonner Beste and its NA-less mutant chloronerva. Contrary to the other heavy metals, copper transport in the xylem was ineffici ent in the mutant and was enhanced by an application of NA to the root s or leaves in proportion to the applied NA concentration. Also, with NA application, the Cu concentration in mutant roots decreased signifi cantly, and increased in the shoot. Fe and Mn transport in the xylem w as greater in the mutant than in the wild type, and was decreased in t he mutant by the application of NA to the leaves. Zn transport in the xylem was the same in both genotypes and was unaffected by NA applicat ion. After application of NA to leaves and roots of the mutant it was possible to detect NA in the xylem exudate (up to 2 nmol NA (g(-1) roo t FW h(-1)). High Cu supply (3 mu M) resulted in higher Cu and Mn conc entrations in all organs of the wild type as compared to mutant organs , but Fe concentrations were not influenced. Under high Cu supply (3 m u M) the NA concentrations of roots and the three youngest leaves of t he wild type were higher than under normal Cu supply (0.3 mu M). The h ighest concentrations were found in the shoot apex under both Cu condi tions (up to 361 nmol NA g(-1) FW). It is concluded from our experimen ts and from the high stability constant of the NA-Cu-complex (log K = 18.6) that NA is involved in Cu translocation whereas for the transloc ation of Fe, Mn, and Zn, NA is not essential.