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 rootsoil 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.

Keywords

Arabidopsis thaliana; arsenate toxicity; phosphate starvation; phosphate transporter; plasma membrane; root branching; Saccharomyces cerevisiae

Published in

New Phytologist
2012, Volume: 195, number: 2, pages: 356-371

UKÄ Subject classification

Plant Biotechnology
Botany


Publication identifier

DOI: https://doi.org/10.1111/j.1469-8137.2012.04167.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/84561