Post-translational regulation of AtFER2 ferritin in response to intracellular iron trafficking during fruit development in Arabidopsis.
Ferritins are major players in plant iron homeostasis. Surprisingly, their overexpression in transgenic plants led only to a moderate increase in seed iron content, suggesting the existence of control checkpoints for iron loading and storage in seeds. This work reports the identification of two of these checkpoints. First, measurement of seed metal content during fruit development in Arabidopsis thaliana reveals a similar dynamic of loading for Fe, Mn, Cu, and Zn. The step controlling metal loading into the seed occurs by the regulation of transport from the hull to the seed. Second, metal loading and ferritin abundance were monitored in different genetic backgrounds affected in vacuolar iron transport (AtVIT1, AtNRAMP3, AtNRAMP4) or plastid iron storage (AtFER1 to 4). This approach revealed (1) a post-translational regulation of ferritin accumulation in seeds, and (2) that ferritin stability depends on the balance of iron allocation between vacuoles and plastids. Thus, the success of ferritin overexpression strategies for iron biofortification, a promising approach to reduce iron-deficiency anemia in developing countries, would strongly benefit from the identification and engineering of mechanisms enabling the translocation of high amounts of iron into seed plastids.
Ravet
Karl
K
Biochimie et Physiologie Moléculaire des Plantes (B&PMP), Unité Mixte de Recherche, CNRS, INRA, Université Montpellier 2, SupAgro, Place Viala, Bat. 7, F-34060 Montpellier, France.
Touraine
Brigitte
B
Kim
Sun A
SA
Cellier
Françoise
F
Thomine
Sébastien
S
Guerinot
Mary Lou
ML
Briat
Jean-François
JF
Gaymard
Frédéric
F
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D007501:Iron / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
D029681:Arabidopsis Proteins; D005293:Ferritins; D007501:Iron