Nitrate-Dependent Control of Shoot K Homeostasis by the Nitrate Transporter1/Peptide Transporter Family Member NPF7.3/NRT1.5 and the Stelar K+ Outward Rectifier SKOR in Arabidopsis.
Root-to-shoot translocation and shoot homeostasis of potassium (K) determine nutrient balance, growth, and stress tolerance of vascular plants. To maintain the cation-anion balance, xylem loading of K(+) in the roots relies on the concomitant loading of counteranions, like nitrate (NO3 (-)). However, the coregulation of these loading steps is unclear. Here, we show that the bidirectional, low-affinity Nitrate Transporter1 (NRT1)/Peptide Transporter (PTR) family member NPF7.3/NRT1.5 is important for the NO3 (-)-dependent K(+) translocation in Arabidopsis (Arabidopsis thaliana). Lack of NPF7.3/NRT1.5 resulted in K deficiency in shoots under low NO3 (-) nutrition, whereas the root elemental composition was unchanged. Gene expression data corroborated K deficiency in the nrt1.5-5 shoot, whereas the root responded with a differential expression of genes involved in cation-anion balance. A grafting experiment confirmed that the presence of NPF7.3/NRT1.5 in the root is a prerequisite for proper root-to-shoot translocation of K(+) under low NO3 (-) supply. Because the depolarization-activated Stelar K(+) Outward Rectifier (SKOR) has previously been described as a major contributor for root-to-shoot translocation of K(+) in Arabidopsis, we addressed the hypothesis that NPF7.3/NRT1.5-mediated NO3 (-) translocation might affect xylem loading and root-to-shoot K(+) translocation through SKOR. Indeed, growth of nrt1.5-5 and skor-2 single and double mutants under different K/NO3 (-) regimes revealed that both proteins contribute to K(+) translocation from root to shoot. SKOR activity dominates under high NO3 (-) and low K(+) supply, whereas NPF7.3/NRT1.5 is required under low NO3 (-) availability. This study unravels nutritional conditions as a critical factor for the joint activity of SKOR and NPF7.3/NRT1.5 for shoot K homeostasis.
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.).
Navina
N
Drechsler
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.).
Yue
Y
Zheng
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.).
Anne
http://orcid.org/0000-0002-2431-101X
A
Bohner
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.).
Barbara
B
Nobmann
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.).
Nicolaus
http://orcid.org/0000-0002-4966-425X
N
von Wirén
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.) reinhard.kunze@fu-berlin.de.
Reinhard
http://orcid.org/0000-0002-3304-5550
R
Kunze
Institute of Biology/Applied Genetics, Dahlem Centre of Plant Sciences, Freie Universität Berlin, D-14195 Berlin, Germany (N.D., Y.Z., B.N., R.K., C.R.); andMolecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research, 06466 Gatersleben, Germany (A.B., N.v.W.).
Christine
C
Rausch
D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D017136:Ion Transport / Q000235:genetics / Q000502:physiology; D009154:Mutation; D009566:Nitrates / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011188:Potassium / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051637:Shaker Superfamily of Potassium Channels / Q000235:genetics / Q000378:metabolism*; D052584:Xylem / Q000235:genetics / Q000378:metabolism / Q000502:physiology
D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; C101492:NRT1.1 protein, Arabidopsis; C539716:NRT1.5 protein, Arabidopsis; D009566:Nitrates; D010940:Plant Proteins; C114544:SKOR protein, Arabidopsis; D051637:Shaker Superfamily of Potassium Channels; D011188:Potassium