title: The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis.
abstract: Iron (Fe) deficiency is a widespread nutritional disorder on calcareous soils. To identify genes involved in the Fe deficiency response, Arabidopsis (Arabidopsis thaliana) transfer DNA insertion lines were screened on a high-pH medium with low Fe availability. This approach identified METAL TOLERANCE PROTEIN8 (MTP8), a member of the Cation Diffusion Facilitator family, as a critical determinant for the tolerance to Fe deficiency-induced chlorosis, also on soil substrate. Subcellular localization to the tonoplast, complementation of a manganese (Mn)-sensitive Saccharomyces cerevisiae yeast strain, and Mn sensitivity of mtp8 knockout mutants characterized the protein as a vacuolar Mn transporter suitable to prevent plant cells from Mn toxicity. MTP8 expression was strongly induced on low-Fe as well as high-Mn medium, which were both strictly dependent on the transcription factor FIT, indicating that high-Mn stress induces Fe deficiency. mtp8 mutants were only hypersensitive to Fe deficiency when Mn was present in the medium, which further suggested an Mn-specific role of MTP8 during Fe limitation. Under those conditions, mtp8 mutants not only translocated more Mn to the shoot than did wild-type plants but suffered in particular from critically low Fe concentrations and, hence, Fe chlorosis, although the transcriptional Fe deficiency response was up-regulated more strongly in mtp8. The diminished uptake of Fe from Mn-containing low-Fe medium by mtp8 mutants was caused by an impaired ability to boost the ferric chelate reductase activity, which is an essential process in Fe acquisition. These findings provide a mechanistic explanation for the long-known interference of Mn in Fe nutrition and define the molecular processes by which plants alleviate this antagonism.
authors.affiliation: Leibniz-Institute for Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany (S.E., N.v.W.); andPlant Nutrition Laboratory, Institute of Agricultural and Nutritional Sciences, Faculty of Natural Sciences III, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany (B.M., E.P.).
authors.forename: Seckin
authors.identifier: http://orcid.org/0000-0002-9494-7080
authors.initials: S
authors.lastname: Eroglu
authors.affiliation: Leibniz-Institute for Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany (S.E., N.v.W.); andPlant Nutrition Laboratory, Institute of Agricultural and Nutritional Sciences, Faculty of Natural Sciences III, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany (B.M., E.P.).
authors.forename: Bastian
authors.identifier: http://orcid.org/0000-0003-3270-5825
authors.initials: B
authors.lastname: Meier
authors.affiliation: Leibniz-Institute for Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany (S.E., N.v.W.); andPlant Nutrition Laboratory, Institute of Agricultural and Nutritional Sciences, Faculty of Natural Sciences III, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany (B.M., E.P.).
authors.forename: Nicolaus
authors.identifier: http://orcid.org/0000-0002-4966-425X
authors.initials: N
authors.lastname: von Wirén
authors.affiliation: Leibniz-Institute for Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany (S.E., N.v.W.); andPlant Nutrition Laboratory, Institute of Agricultural and Nutritional Sciences, Faculty of Natural Sciences III, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany (B.M., E.P.) edgar.peiter@landw.uni-halle.de.
authors.forename: Edgar
authors.identifier: http://orcid.org/0000-0002-9104-3238
authors.initials: E
authors.lastname: Peiter
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D027682:Cation Transport Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D038181:FMN Reductase / Q000378:metabolism; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D000090463:Iron Deficiencies; D008345:Manganese / Q000378:metabolism* / Q000494:pharmacology; D016254:Mutagenesis, Insertional / Q000235:genetics; D009154:Mutation / Q000235:genetics; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D004269:DNA, Bacterial; C000611829:MTP8 protein, Arabidopsis; C036483:T-DNA; D008345:Manganese; D038181:FMN Reductase; C023903:ferric citrate iron reductase