CHARACTERISTICS OF LIGHT-REGULATED IRON TRANSPORT-SYSTEM IN BARLEY CHLOROPLASTS (REPRINTED FROM PLANT NUTRITION FOR SUSTAINABLE FOOD-PRODUCTION AND ENVIRONMENT, 1997)

Fe absorption was examined using chloroplasts, isolated from leaves of hydroponically cultured Fe-sufficient barley plants, to clarify the m echanism underlying the light-dependent Fe-influx into the chloroplast s. Inhibitors of Fe transport, ATP and proton flux were employed. Fe t ransport into the chloroplasts was partially inhibited by bathophenant hrolinedisulfonic acid (BPDS), which suggested the involvement of Fe3-reductase in the process of transmembrane Fe-influx. We also found th at adenosine triphosphate (ATP:) and proton (H+) flux were not the cau se of transmembrane Fe transport. The optimum pH for Fe transport acro ss the chloroplast envelope was 8.0. However, a sharp increase in the Fe absorption was observed in pH range of 7.0 to 7.5. Fe transport int o the chloroplasts was unaffected by the presence of Zn, Cu, Ni, Mn, C o or Cd in the medium at 1 x 10(-5) or 1 x 10(-4) M concentration.