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A 150 kDa plasma membrane complex of AtNRT 2.5 and AtNAR 2.1 is the major contributor to constitutive high‐affinity nitrate influx in A rabidopsis thaliana
Author(s) -
KOTUR ZORICA,
GLASS ANTHONY D. M.
Publication year - 2015
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12496
Subject(s) - nitrate , mutant , transporter , chemistry , biochemistry , arabidopsis thaliana , arabidopsis , wild type , microbiology and biotechnology , biology , gene , organic chemistry
Abstract In plants that have been deprived of nitrate for a significant length of time, a c onstitutive h igh‐ a ffinity nitrate t ransport s ystem ( cHATS ) is responsible for initial nitrate uptake. This absorbed nitrate leads to the induction of the major nitrate transporters and enzymes involved in nitrate assimilation. By use of 13 NO 3 – influx measurements and B lue N ative polyacrylamide gel electrophoresis we examined the role of AtNRT 2.5 in cHATS in wild type ( WT ) and various T‐DNA mutants of A rabidopsis thaliana . We demonstrate that AtNRT 2.5 is predominantly expressed in roots of nitrate‐deprived WT plants as a 150 kDa molecular complex with AtNAR2 .1. This complex represents the major contributor to cHATS influx, which is reduced by 63% compared with WT in roots of A tnrt2.5 mutants. The remaining cHATS nitrate influx in these mutants is due to a residual contribution by the inducible high‐affinity transporter encoded by AtNRT 2.1/ AtNAR 2.1. Estimates of the kinetic properties of the NRT2 .5 transporter reveal that its low K m for nitrate makes this transporter ideally suited to detect and respond to trace quantities of nitrate in the root environment.