A 150 kDa plasma membrane complex of AtNRT2.5 and AtNAR2.1 is the major contributor to constitutive high‐affinity nitrate influx in Arabidopsis thaliana. (31st January 2015)

• Record Type: Journal Article
• Authors: KOTUR, ZORICA; GLASS, ANTHONY D. M.
• Is Part Of: Plant, cell and environment. Volume 38:Number 8(2015:Aug.)
• Page Start: 1490
• Page End: 1502
• Publication Date: 2015-01-31
• Subjects: Plant physiology -- Periodicals; Plant cells and tissues -- Periodicals; Plant communities -- Periodicals; 581.105
• DOI: 10.1111/pce.12496
• Languages: English
• ISSNs: 0140-7791

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>In plants that have been deprived of nitrate for a significant length of time, a <italic>c</italic>onstitutive <italic>h</italic>igh‐<italic>a</italic>ffinity nitrate <italic>t</italic>ransport <italic>s</italic>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 ¹³NO₃^– influx measurements and Blue Native polyacrylamide gel electrophoresis we examined the role of AtNRT2.5 in cHATS in wild type (WT) and various T‐DNA mutants of <italic>A</italic><italic>rabidopsis thaliana</italic>. We demonstrate that <italic>AtNRT</italic><italic>2.5</italic> 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 <italic>A</italic><italic>tnrt2.5</italic> mutants. The remaining cHATS nitrate influx in these mutants is due to a residual contribution by the inducible high‐affinity transporter encoded by AtNRT2.1/AtNAR2.1. Estimates of the kinetic properties of the NRT2.5 transporter reveal that its low <italic>K</italic>_m for nitrate makes this transporter ideally suited to detect and respond to trace quantities of nitrate in the root environment.</p> </abstract>