Zinc in Plant Nutrition, Nature of Zinc-Containing Substances in Alfalfa Plant Cell

Abstract

Alfalfa plants grown in nutrient solution containing Zn65 as a tracer were blended with water or a buffer and centrifuged. The supernatant liquid containing the cytoplasm was used for studies concerning the nature of zinc and zinc-containing substances in alfalfa plant cells. Presence of free zinc ions was shown by H2S precipitation and by removal of Zn65 by dialysis of the plant extract.Binding of zinc was observed in equilibrium dialysis experiments. Trichloroacetic acid precipitation of protein in a plant extract removed 25% of the Zn65. Paper electrophoresis of buffered plant extract indicated zinc-protein binding. Apparently zinc is both free and bound, and an equilibrium exists such as: