The Role of Iron-Deficiency Stress Responses in Stimulating Heavy-Metal Transport in Plants1
- 1 March 1998
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 116 (3), 1063-1072
- https://doi.org/10.1104/pp.116.3.1063
Abstract
Plant accumulation of Fe and other metals can be enhanced under Fe deficiency. We investigated the influence of Fe status on heavy-metal and divalent-cation uptake in roots of pea (Pisum sativum L. cv Sparkle) seedlings using Cd2+ uptake as a model system. Radiotracer techniques were used to quantify unidirectional 109Cd influx into roots of Fe-deficient and Fe-sufficient pea seedlings. The concentration-dependent kinetics for 109Cd influx were graphically complex and nonsaturating but could be resolved into a linear component and a saturable component exhibiting Michaelis-Menten kinetics. We demonstrated that the linear component was apoplastically bound Cd2+ remaining in the root cell wall after desorption, whereas the saturable component was transporter-mediated Cd2+ influx across the root-cell plasma membrane. The Cd2+ transport system in roots of both Fe-deficient and Fe-sufficient seedlings exhibited similar Michaelis constant values, 1.5 and 0.6 μm, respectively, for saturable Cd2+ influx, whereas the maximum initial velocity for Cd2+ uptake in Fe-deficient seedlings was nearly 7-fold higher than that in Fe-grown seedlings. Investigations into the mechanistic basis for this response demonstrated that Fe-deficiency-induced stimulation of the plasma membrane H+-ATPase did not play a role in the enhanced Cd2+ uptake. Expression studies with the Fe2+transporter cloned from Arabidopsis, IRT1, indicated that Fe deficiency induced the expression of this transporter, which might facilitate the transport of heavy-metal divalent cations such as Cd2+ and Zn2+, in addition to Fe2+.Keywords
This publication has 26 references indexed in Scilit:
- Genetic evidence that induction of root Fe(III) chelate reductase activity is necessary for iron uptake under iron deficiency†The Plant Journal, 1996
- The Gene Encodes the Low Affinity Zinc Transporter inPublished by Elsevier BV ,1996
- A Permease-Oxidase Complex Involved in High-Affinity Iron Uptake in YeastScience, 1996
- Iron Nutrition Influence on Cadmium Accumulation by Arabidopsis thaliana (L.) Heynh.Journal of Environmental Quality, 1994
- The FET3 gene of S. cerevisiae encodes a multicopper oxidase required for ferrous iron uptakeCell, 1994
- Physiological Characterization of a Single-Gene Mutant of Pisum sativum Exhibiting Excess Iron AccumulationPlant Physiology, 1990
- Iron-Stress Induced Redox Activity in Tomato (Lycopersicum esculentum Mill.) Is Localized on the Plasma MembranePlant Physiology, 1989
- Mechanisms in Fe‐efficiency reactions of higher plantsJournal of Plant Nutrition, 1988
- pH Changes Associated with Iron-Stress ResponsePhysiologia Plantarum, 1974
- Obligatory Reduction of Ferric Chelates in Iron Uptake by SoybeansPlant Physiology, 1972