The Pht1;9 and Pht1;8 transporters mediate inorganic phosphate acquisition by the Arabidopsis thaliana root during phosphorus starvation

New Phytol. 2012 Jul;195(2):356-71. doi: 10.1111/j.1469-8137.2012.04167.x. Epub 2012 May 11.

Abstract

• The activation of high-affinity root transport systems is the best-conserved strategy employed by plants to cope with low inorganic phosphate (Pi) availability, a role traditionally assigned to Pi transporters of the Pht1 family, whose respective contributions to Pi acquisition remain unclear. • To characterize the Arabidopsis thaliana Pht1;9 transporter, we combined heterologous functional expression in yeast with expression/subcellular localization studies and reverse genetics approaches in planta. Double Pht1;9/Pht1;8 silencing lines were also generated to gain insight into the role of the closest Pht1;9 homolog. • Pht1;9 encodes a functional plasma membrane-localized transporter that mediates high-affinity Pi/H⁺ symport activity in yeast and is highly induced in Pi-starved Arabidopsis roots. Null pht1;9 alleles exhibit exacerbated responses to prolonged Pi limitation and enhanced tolerance to arsenate exposure, whereas Pht1;9 overexpression induces the opposite phenotypes. Strikingly, Pht1;9/Pht1;8 silencing lines display more pronounced defects than the pht1;9 mutants. • Pi and arsenic plant content analyses confirmed a role of Pht1;9 in Pi acquisition during Pi starvation and arsenate uptake at the root-soil interface. Although not affecting plant internal Pi repartition, Pht1;9 activity influences the overall Arabidopsis Pi status. Finally, our results indicate that both the Pht1;9 and Pht1;8 transporters function in sustaining plant Pi supply on environmental Pi depletion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / drug effects
  • Adaptation, Physiological / genetics
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Arsenates / toxicity
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Gene Expression Regulation, Plant / drug effects
  • Genes, Plant / genetics
  • Phenotype
  • Phosphate Transport Proteins / genetics
  • Phosphate Transport Proteins / metabolism*
  • Phosphates / metabolism*
  • Phosphorus / deficiency*
  • Phosphorus / pharmacology
  • Plant Roots / drug effects
  • Plant Roots / genetics
  • Plant Roots / metabolism*
  • Plants, Genetically Modified
  • Proton-Phosphate Symporters / metabolism
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / metabolism
  • Subcellular Fractions / drug effects
  • Subcellular Fractions / metabolism

Substances

  • Arabidopsis Proteins
  • Arsenates
  • Phosphate Transport Proteins
  • Phosphates
  • Pht1;8 protein, Arabidopsis
  • Pht1;9 protein, Arabidopsis
  • Proton-Phosphate Symporters
  • Phosphorus
  • arsenic acid