Partner und Internationale Organisationen
(Englisch)
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AT, BE, BG, CH, CZ, DE, DK, EE, ES, FI, FR, GR, IE, IT, LT, LU, NL, NO, PL, PT, RS, SE, SI, SK, UK
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Abstract
(Englisch)
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Zinc (Zn) is an essential microelement in all organisms responsible for structural and functional aspects at all developmental and metabolic stages but it is toxic in excess. Several plant species are able to accumulate Zn in extraordinary high concentrations in the leaf epidermis without showing any toxicity symptoms. However the molecular mechanisms of this process are still poorly understood. A state-of-the-art quantitative 2D-liquid-chromatography tandem mass-spectrometry (2D-LC-MS/MS) proteomics approach was performed to investigate the abundance of proteins involved in Zn hyperaccumulation in Thalspi caerulescens leaf epidermal and mesophyll tissues. Quantitation of protein abundances was performed based on spectral counting. Furthermore, zinc speciation was analyzed in more detail to identify the repective mechanisms responsible for ZN hyperaccumulation. A Zn importer of the ZIP family and the vacuolar Zn transporter MTP1 were more abundant in the epidermal tissue. Almost all of the Zn located in the mesophyll tissue was stored as Zn nicotianamine (NA) complex, but a far lower proportion is found as NA complex in the epidermis. However, these cells contain higher concentrations of malate and citrate, which are probably responsible for the chelation of the major part of zinc in the epidermis. In our study, we provide evidence for a cell type specific adaptation to high excess Zn conditions and to an increased ability to transport Zn into the epidermal vacuoles.
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