Ascorbate efflux as a new strategy for iron reduction and transport in plants. - Archive ouverte HAL Access content directly
Journal Articles Journal of Biological Chemistry Year : 2014

Ascorbate efflux as a new strategy for iron reduction and transport in plants.


Iron (Fe) is essential for virtually all living organisms. The identification of the chemical forms of iron (the speciation) circulating in and between cells is crucial to further understand the mechanisms of iron delivery to its final targets. Here we analyzed how iron is transported to the seeds by the chemical identification of iron complexes that are delivered to embryos, followed by the biochemical characterization of the transport of these complexes by the embryo, using the pea (Pisum sativum) as a model species. We have found that iron circulates as ferric complexes with citrate and malate (Fe(III)3Cit2Mal2, Fe(III)3Cit3Mal1, Fe(III)Cit2). Because dicotyledonous plants only transport ferrous iron, we checked whether embryos were capable of reducing iron of these complexes. Indeed, embryos did express a constitutively high ferric reduction activity. Surprisingly, iron(III) reduction is not catalyzed by the expected membrane-bound ferric reductase. Instead, embryos efflux high amounts of ascorbate that chemically reduce iron(III) from citrate-malate complexes. In vitro transport experiments on isolated embryos using radiolabeled (55)Fe demonstrated that this ascorbate-mediated reduction is an obligatory step for the uptake of iron(II). Moreover, the ascorbate efflux activity was also measured in Arabidopsis embryos, suggesting that this new iron transport system may be generic to dicotyledonous plants. Finally, in embryos of the ascorbate-deficient mutants vtc2-4, vtc5-1, and vtc5-2, the reducing activity and the iron concentration were reduced significantly. Taken together, our results identified a new iron transport mechanism in plants that could play a major role to control iron loading in seeds.
Fichier principal
Vignette du fichier
2014_Grillet_Journal of Biological Chemistry_1.pdf (1.21 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

hal-00945537 , version 1 (28-05-2020)





Louis Grillet, Laurent Ouerdane, Paulina Flis, Minh Thi Thanh Hoang, M.-P. Isaure, et al.. Ascorbate efflux as a new strategy for iron reduction and transport in plants.. Journal of Biological Chemistry, 2014, 289 (5), pp.2515-25. ⟨10.1074/jbc.M113.514828⟩. ⟨hal-00945537⟩
128 View
64 Download



Gmail Facebook Twitter LinkedIn More