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Iron Uptake by Symbiosomes from Soybean Root Nodules
K. LeVier1, D. A. Day, M. L. Guerinot
1Department of Biological Sciences, 6044 Gilman, Dartmouth College, Hanover, New Hampshire 03755 (K.L., M.L.G.).
Plant Physiology
|July 1, 1996
Summary
Soybean symbiosomes possess an iron storage pool within the peribacteroid space. Ferric-chelate reductase activity in the peribacteroid membrane aids iron transport into bacteroids.
Area of Science:
- Plant-microbe interactions
- Molecular plant science
- Biochemistry
Background:
- Bacteroids in soybean symbiosomes require iron for nitrogen fixation.
- The precise mechanisms of iron uptake into symbiosomes are not fully understood.
Purpose of the Study:
- To investigate iron transport pathways into soybean symbiosomes.
- To identify potential iron storage sites and transport mechanisms.
Main Methods:
- Assaying iron transport across peribacteroid membranes (PBM) and bacteroid membranes using ferric [Fe(III)]-chelates.
- Conducting pulse-chase experiments to track iron movement.
- Detecting ferric-chelate reductase activity associated with the PBM.
Main Results:
- Iron transport occurred at higher rates across the PBM than bacteroid membranes.
- Pulse-chase experiments confirmed an iron storage pool in the peribacteroid space.
- Ferric-chelate reductase activity was detected in the PBM.
Conclusions:
- Soybean symbiosomes likely store iron in the peribacteroid space.
- Reduction of Fe(III) to Fe(II) by PBM-associated ferric-chelate reductase may facilitate iron movement into symbiosomes.
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