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Title: Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. [Phadeolus vulgaris L. var Prelude]

Abstract

The recent proposal of Tipton and Thowsen that iron-deficient plants reduce ferric chelates in cell walls by a system dependent on the leakage of malate from root cells was tested. Results are presented showing that this mechanism could not be responsible for the high rates of ferric reduction shown by roots of iron-deficient bean (Phaseolus vulgaris L. var Prelude) plants. The role of O/sub 2/ in the reduction of ferric chelates by roots of iron-deficient bean plants was also tested. The rate of Fe(III) reduction was the same in the presence and in the absence of O/sub 2/. However, in the presence of O/sub 2/ the reaction was partially inhibited by superoxide dismutase (SOD), which indicates a role for the superoxide radical, O/sub 2//sup -/, as a facultative intermediate electron carrier. The inhibition by SOD increased with substrate pH and with decrease in concentration of the ferrous scavenger bathophenanthroline-disulfonate. The results are consistent with a mechanism for transmembrane electron in which a flavin or quinone is the final electron carrier in the plasma membrane. The results are discussed in relation to the ecological importance that O/sub 2//sup -/ may have in the acquisition of ferric iron by dicotyledonous plants.

Authors:
; ; ;
Publication Date:
Research Org.:
Universitaet Hohenheim, Stuttgart (West Germany)
OSTI Identifier:
6998485
Alternate Identifier(s):
OSTI ID: 6998485
Resource Type:
Journal Article
Resource Relation:
Journal Name: Plant Physiol.; (United States); Journal Volume: 85:1
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; IRON COMPOUNDS; REDUCTION; PHASEOLUS; NUTRITIONAL DEFICIENCY; ROOTS; SUPEROXIDE DISMUTASE; BIOCHEMICAL REACTION KINETICS; INHIBITION; MEMBRANE TRANSPORT; OXYGEN; PH VALUE; RESPONSE MODIFYING FACTORS; SCAVENGING; SUPEROXIDE RADICALS; BACTERIA; CHEMICAL REACTIONS; ELEMENTS; ENZYMES; KINETICS; LEGUMINOSAE; MICROORGANISMS; NONMETALS; OXIDOREDUCTASES; PLANTS; RADICALS; REACTION KINETICS; RHIZOBIUM; TRANSITION ELEMENT COMPOUNDS 550200* -- Biochemistry

Citation Formats

Cakmak, I., van de Wetering, D.A.M., Marschner, H., and Bienfait, H.F.. Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. [Phadeolus vulgaris L. var Prelude]. United States: N. p., 1987. Web.
Cakmak, I., van de Wetering, D.A.M., Marschner, H., & Bienfait, H.F.. Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. [Phadeolus vulgaris L. var Prelude]. United States.
Cakmak, I., van de Wetering, D.A.M., Marschner, H., and Bienfait, H.F.. Tue . "Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. [Phadeolus vulgaris L. var Prelude]". United States. doi:.
@article{osti_6998485,
title = {Involvement of superoxide radical in extracellular ferric reduction by iron-deficient bean roots. [Phadeolus vulgaris L. var Prelude]},
author = {Cakmak, I. and van de Wetering, D.A.M. and Marschner, H. and Bienfait, H.F.},
abstractNote = {The recent proposal of Tipton and Thowsen that iron-deficient plants reduce ferric chelates in cell walls by a system dependent on the leakage of malate from root cells was tested. Results are presented showing that this mechanism could not be responsible for the high rates of ferric reduction shown by roots of iron-deficient bean (Phaseolus vulgaris L. var Prelude) plants. The role of O/sub 2/ in the reduction of ferric chelates by roots of iron-deficient bean plants was also tested. The rate of Fe(III) reduction was the same in the presence and in the absence of O/sub 2/. However, in the presence of O/sub 2/ the reaction was partially inhibited by superoxide dismutase (SOD), which indicates a role for the superoxide radical, O/sub 2//sup -/, as a facultative intermediate electron carrier. The inhibition by SOD increased with substrate pH and with decrease in concentration of the ferrous scavenger bathophenanthroline-disulfonate. The results are consistent with a mechanism for transmembrane electron in which a flavin or quinone is the final electron carrier in the plasma membrane. The results are discussed in relation to the ecological importance that O/sub 2//sup -/ may have in the acquisition of ferric iron by dicotyledonous plants.},
doi = {},
journal = {Plant Physiol.; (United States)},
number = ,
volume = 85:1,
place = {United States},
year = {Tue Sep 01 00:00:00 EDT 1987},
month = {Tue Sep 01 00:00:00 EDT 1987}
}