title: Iron Uptake by Symbiosomes from Soybean Root Nodules.
abstract: To identify possible iron sources for bacteroids in planta, soybean (Glycine max L. Merr.) symbiosomes (consisting of the bacteroid-containing peribacteroid space enclosed by the peribacteroid membrane [PBM]) and bacteroids were assayed for the ability to transport iron supplied as various ferric [Fe(III)]-chelates. Iron presented as a number of Fe(III)-chelates was transported at much higher rates across the PBM than across the bacteroid membranes, suggesting the presence of an iron storage pool in the peribacteroid space. Pulse-chase experiments confirmed the presence of such an iron storage pool. Because the PBM is derived from the plant plasma membrane, we reasoned that it may possess a ferric-chelate reductase activity similar to that present in plant plasma membrane. We detected ferric-chelate reductase activity associated with the PBM and suggest that reduction of Fe(III) to ferrous [Fe(II)] plays a role in the movement of iron into soybean symbiosomes.
authors.affiliation: Department of Biological Sciences, 6044 Gilman, Dartmouth College, Hanover, New Hampshire 03755 (K.L., M.L.G.).
authors.forename: K.
authors.initials: K
authors.lastname: LeVier
authors.forename: D. A.
authors.initials: DA
authors.lastname: Day
authors.forename: M. L.
authors.initials: ML
authors.lastname: Guerinot