Premium
Role of AMT1;1 in NH 4 + Acquisition in Arabidopsis thaliana
Author(s) -
Mayer M.,
Ludewig U.
Publication year - 2006
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2006-923877
Subject(s) - photorespiration , biology , pericycle , arabidopsis thaliana , ammonium , xenopus , apoplast , arabidopsis , root hair , epidermis (zoology) , biophysics , microbiology and biotechnology , shoot , biochemistry , botany , photosynthesis , gene , mutant , chemistry , anatomy , cell wall , organic chemistry
AtAMT1;1 was the founding member of the family of AMT/Rh ammonium transporters and accounts for about one third of the total ammonium absorption in the roots of the model plant Arabidopsis. Recent evidence suggested that at least some AMT/Rh proteins are NH 3 gas channels. In order to evaluate the transported form of ammonium in AtAMT1;1, the protein was functionally expressed in Xenopus oocytes. AtAMT1;1 elicited NH 4 + and methylammonium (MeA+) inward currents that saturated in a voltage‐dependent manner with a half maximal concentration of 2.7 ± 1.6 μM for NH 4 + and 5.0 ± 0.7 μM for the transport analogue methylammonium. AtAMT1;1 was plasma membrane localized and expressed in the root cortex and epidermis, including root hairs. The AtAMT1;1‐GFP fusion construct under control of its endogenous promoter revealed additional localization of the protein in the pericycle, in the leaf epidermis, and in mesophyll cells. The functional data and its localization suggest that AtAMT1;1 participates in concentrative NH 4 + acquisition in roots, in long‐distance transport to the shoots, and in re‐uptake of apoplastic NH 4 + that derives from photorespiration in shoots.