Expression analysis suggests novel roles for the plastidic phosphate transporter Pht2;1 in auto- and heterotrophic tissues in potato and Arabidopsis

Authors

  • Christine Rausch,

    1. Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Plant Biochemistry & Physiology Group, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland, and
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  • Philip Zimmermann,

    1. Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Regulatory Networks/Plant Biotechnology, ETH Zentrum, Universtitätsstrasse 2, 8092 Zurich, Switzerland
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  • Nikolaus Amrhein,

    1. Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Plant Biochemistry & Physiology Group, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland, and
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  • Marcel Bucher

    Corresponding author
    1. Federal Institute of Technology (ETH) Zurich, Institute of Plant Sciences, Plant Biochemistry & Physiology Group, Experimental Station Eschikon 33, CH-8315 Lindau, Switzerland, and
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For correspondence (fax +41 52 3549219; e-mail marcel.bucher@ipw.biol.ethz.ch).

Summary

A cDNA encoding Pht2;1 from potato, a new member of the plant Pht2 gene family of low-affinity orthophosphate (Pi) transporters, was isolated. The expression pattern of the corresponding gene as well as its ortholog from Arabidopsis was analyzed and the encoded proteins were localized in the two plants. Pht2;1 expression is strongly upregulated by light in potato and Arabidopsis leaf tissue. RNA gel blot analysis, reverse transcription-polymerase chain reaction (RT-PCR), promoter/GUS, and protein/green fluorescent protein (GFP) fusion studies, respectively, indicate that the gene is expressed in both auto- and heterotrophic tissues and its encoded protein is localized to the plastids. The similar patterns of Pht2;1 gene regulation in potato and Arabidopsis prompted us to screen publicly available gene expression data from 228 Arabidopsis oligonucleotide microarrays covering 83 different experimental conditions. Modulation of Pht2;1 transcript levels was overall moderate, except for a limited number of experimental conditions where Pht2;1 mRNA concentrations varied between 2- and 3.7-fold. Overall, these analyses suggest involvement of the Pht2;1 protein in cell wall metabolism in young, rapidly growing tissues, independent of other Pi transporters such as the high-affinity Solanum tuberosum Pi transporter 1 (StPT1). Cluster analysis allowed identification of colinear or antiparallel expression profiles of a small set of genes involved in post-translational regulation, and photosynthetic carbon metabolism. These data give clues about the possible biological function of Pht2;1 and shed light on the complex web of interactions in which Pht2;1 could play a role.

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