The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis

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2016-02-01
Eroğlu, Seçkin
Meier, Bastian
von Wiren, Nicolaus
Peiter, Edgar
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.

Citation Formats
S. Eroğlu, B. Meier, N. von Wiren, and E. Peiter, “The Vacuolar Manganese Transporter MTP8 Determines Tolerance to Iron Deficiency-Induced Chlorosis in Arabidopsis,” PLANT PHYSIOLOGY, vol. 170, no. 2, pp. 1030–1045, 2016, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/35620.