Distribution of nicotianamine, a presumed symplast iron transporter, in different organs of sunflower and of a tomato wild type and its mutant chloronerva.

Summary The nicotianamine (NA) concentration in the shoot apex of Helianthus annuus amounts to the 2- to 16-fold in comparison to older leaves and cotyledons, and that of apical root zones to the 4-fold in relation to the basal root zones of lateral roots of 2nd order. The NA concentration in leaves and roots of the NA-auxotroph tomato mutant chloronerva , phenotypically normalized by external NA supply, is only about one tenth as compared with the respective wild type tissues. Mutant seeds which developed on scions grafted upon NA-containing wild type rootstocks contained only about the half of the wild type. The high NA concentrations in young rapidly growing sunflower tissues and the different NA contents in tissues of untreated and phenotypically normalized mutant plants are discussed in the light of the postulated role of NA as a symplast iron transporter.