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: Seckin Eroglu, Bastian Meier, Nicolaus von Wirén, Edgar Peiter
• Journal: Plant physiology (Plant Physiol) Vol. 170 Issue 2 Pg. 1030-45 (Feb 2016) ISSN: 1532-2548 [Electronic] United States
• PMID: 26668333 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2016 American Society of Plant Biologists. All Rights Reserved.

Chemical References

• Arabidopsis Proteins
• Cation Transport Proteins
• DNA, Bacterial
• MTP8 protein, Arabidopsis
• T-DNA
• Manganese
• FMN Reductase
• ferric citrate iron reductase

Topics

• Arabidopsis (genetics, growth & development, metabolism, physiology)
• Arabidopsis Proteins (metabolism)
• Biological Transport (drug effects)
• Cation Transport Proteins (metabolism)
• DNA, Bacterial (genetics)
• FMN Reductase (metabolism)
• Gene Knockout Techniques
• Genetic Complementation Test
• Iron Deficiencies
• Manganese (metabolism, pharmacology)
• Mutagenesis, Insertional (genetics)
• Mutation (genetics)
• Plant Roots (drug effects, metabolism)
• Plants, Genetically Modified
• Promoter Regions, Genetic (genetics)
• Saccharomyces cerevisiae (metabolism)
• Seedlings (drug effects, metabolism)
• Up-Regulation (drug effects)
• Vacuoles (metabolism)