title: A vacuolar phosphate transporter essential for phosphate homeostasis in Arabidopsis.
abstract: Inorganic phosphate (Pi) is stored in the vacuole, allowing plants to adapt to variable Pi availability in the soil. The transporters that mediate Pi sequestration into vacuole remain unknown, however. Here we report the functional characterization of Vacuolar Phosphate Transporter 1 (VPT1), an SPX domain protein that transports Pi into the vacuole in Arabidopsis. The vpt1 mutant plants were stunted and consistently retained less Pi than wild type plants, especially when grown in medium containing high levels of Pi. In seedlings, VPT1 was expressed primarily in younger tissues under normal conditions, but was strongly induced by high-Pi conditions in older tissues, suggesting that VPT1 functions in Pi storage in young tissues and in detoxification of high Pi in older tissues. As a result, disruption of VPT1 rendered plants hypersensitive to both low-Pi and high-Pi conditions, reducing the adaptability of plants to changing Pi availability. Patch-clamp analysis of isolated vacuoles showed that the Pi influx current was severely reduced in vpt1 compared with wild type plants. When ectopically expressed in Nicotiana benthamiana mesophyll cells, VPT1 mediates vacuolar influx of anions, including Pi, SO4(2-), NO3(-), Cl(-), and malate with Pi as that preferred anion. The VPT1-mediated Pi current amplitude was dependent on cytosolic phosphate concentration. Single-channel analysis showed that the open probability of VPT1 was increased with the increase in transtonoplast potential. We conclude that VPT1 is a transporter responsible for vacuolar Pi storage and is essential for Pi adaptation in Arabidopsis.
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China;
authors.forename: Jinlong
authors.initials: J
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China;
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China;
authors.forename: Mingda
authors.initials: M
authors.lastname: Luan
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China;
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China;
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China;
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University, Nanjing 210037, China;
authors.forename: Jisen
authors.initials: J
authors.lastname: Shi
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China; fgzhao@nju.edu.cn lanw@nju.edu.cn sluan@berkeley.edu.
authors.forename: Fu-Geng
authors.initials: FG
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China; fgzhao@nju.edu.cn lanw@nju.edu.cn sluan@berkeley.edu.
authors.forename: Wenzhi
authors.initials: W
authors.lastname: Lan
authors.affiliation: State Key Laboratory for Pharmaceutical Biotechnology, Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing 210093, China; Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720 fgzhao@nju.edu.cn lanw@nju.edu.cn sluan@berkeley.edu.
authors.forename: Sheng
authors.initials: S
authors.lastname: Luan
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004777:Environment; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D028061:Phosphate Transport Proteins / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism* / Q000494:pharmacology; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D028061:Phosphate Transport Proteins; D010710:Phosphates; C000605822:VPT1 protein, Arabidopsis; D049452:Green Fluorescent Proteins
keywords: anion channel; patch clamp; phosphorus nutrition; vacuolar phosphate sequestration