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

• Published in: The New phytologist Vol. 195; no. 2; pp. 356 - 371
• Main Authors: Remy, E., Cabrito, T. R., Batista, R. A., Teixeira, M. C., Sá‐Correia, I., Duque, P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK New Phytologist Trust 01.07.2012; Blackwell Publishing Ltd; Wiley Subscription Services, Inc
• Subjects: Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Affinity; Alleles; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; arsenate toxicity; Arsenates; Arsenates - toxicity; Arsenic; Cell Membrane - drug effects; Cell Membrane - metabolism; Defects; Depletion; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant - genetics; Genetics; Homology; Localization; Phenotype; Phenotypes; phosphate starvation; Phosphate starvation response; Phosphate transport proteins; Phosphate Transport Proteins - genetics; Phosphate Transport Proteins - metabolism; phosphate transporter; Phosphates; Phosphates - metabolism; Phosphorus; Phosphorus - deficiency; Phosphorus - pharmacology; Plant cells; Plant roots; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - metabolism; Plants; Plants, Genetically Modified; plasma membrane; Proton-Phosphate Symporters - metabolism; root branching; Saccharomyces cerevisiae; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - metabolism; Seedlings; Starvation; Subcellular Fractions - drug effects; Subcellular Fractions - metabolism; Symport; Transportation systems; Uptake; Yeast; Yeasts
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2012.04167.x

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.