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A proteomics approach to investigate the process of Z n hyperaccumulation in N occaea caerulescens ( J & C . P resl) F . K . M eyer
Author(s) -
Schneider Thomas,
Persson Daniel Pergament,
Husted Søren,
Schellenberg Maja,
Gehrig Peter,
Lee Youngsook,
Martinoia Enrico,
Schjoerring Jan K.,
Meyer Stefan
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12022
Subject(s) - chemistry , epidermis (zoology) , zinc , efflux , biochemistry , mass spectrometry , tandem mass spectrometry , glutathione , transporter , chromatography , enzyme , biology , gene , anatomy , organic chemistry
Summary Zinc ( Z n) is an essential trace element in all living organisms, but is toxic in excess. Several plant species are able to accumulate Z n at extraordinarily high concentrations in the leaf epidermis without showing any toxicity symptoms. However, the molecular mechanisms of this phenomenon are still poorly understood. A state‐of‐the‐art quantitative 2 D liquid chromatography/tandem mass spectrometry (2 D ‐ LC ‐ MS / MS ) proteomics approach was used to investigate the abundance of proteins involved in Z n hyperaccumulation in leaf epidermal and mesophyll tissues of N occaea caerulescens . Furthermore, the Z n speciation in planta was analyzed by a size‐exclusion chromatography/inductively coupled plasma mass spectrometer ( SEC ‐ ICP ‐ MS ) method, in order to identify the Z n‐binding ligands and mechanisms responsible for Z n hyperaccumulation. Epidermal cells have an increased capability to cope with the oxidative stress that results from excess Z n, as indicated by a higher abundance of glutathione S ‐transferase proteins. A Z n importer of the ZIP family was more abundant in the epidermal tissue than in the mesophyll tissue, but the vacuolar Z n transporter MTP 1 was equally distributed. Almost all of the Z n located in the mesophyll was stored as Z n–nicotianamine complexes. In contrast, a much lower proportion of the Z n was found as Z n–nicotianamine complexes in the epidermis. However, these cells have higher concentrations of malate and citrate, and these organic acids are probably responsible for complexation of most epidermal Z n. Here we provide evidence for a cell type‐specific adaptation to excess Z n conditions and an increased ability to transport Z n into the epidermal vacuoles.