Selenate-resistant mutants of Arabidopsis thaliana identify Sultr1;2, a sulfate transporter required for efficient transport of sulfate into roots

Authors

  • Nakako Shibagaki,

    1. Department of Botany, Iowa State University, Ames, Iowa 50011, USA,
    2. Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan, and
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  • Alan Rose,

    1. Section of Molecular and Cellular Biology, Division of Biological Sciences, University of California, Davis, 1 Shields Avenue, Davis, California 95616, USA
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  • Jeffrey P. McDermott,

    1. Department of Botany, Iowa State University, Ames, Iowa 50011, USA,
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  • Toru Fujiwara,

    1. Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan, and
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  • Hiroaki Hayashi,

    1. Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan, and
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  • Tadakatsu Yoneyama,

    1. Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, the University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan, and
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  • John P. Davies

    Corresponding author
    1. Department of Botany, Iowa State University, Ames, Iowa 50011, USA,
      * For correspondence (fax +1 503 670 7703; e-mail jdavies@exelixis.com
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    • Current address: Exelixis Plant Sciences, 16160 SW Upper Boones Ferry Road, Portland, Oregon 97224-7744, USA.


* For correspondence (fax +1 503 670 7703; e-mail jdavies@exelixis.com).

Summary

To investigate how plants acquire and assimilate sulfur from their environment, we isolated and characterized two mutants of Arabidopsis thaliana deficient in sulfate transport. The mutants are resistant to selenate, a toxic analogue of sulfate. They are allelic to each other and to the previously isolated sel1 (selenate-resistant) mutants, and have been designated sel1-8 and sel1-9. Root elongation in these mutants is less sensitive to selenate than in wild-type plants. Sulfate uptake into the roots is impaired in the mutants under both sulfur-sufficient and sulfur-deficient conditions, but transport of sulfate to the shoot is not affected. The sel1 mutants contain lesions in the sulfate transporter gene Sultr1;2 located on the lower arm of chromosome 1. The sel1-1, sel1-3 and sel1-8 mutants contain point mutations in the coding sequences of Sultr1;2, while the sel1-9 mutant has a T-DNA insertion in the Sultr1;2 promoter. The Sultr1;2 cDNA derived from wild-type plants is able to complement Saccharomyces cerevisiae mutants defective in sulfate transport, but the Sultr1;2 cDNA from sel1-8 is not. The Sultr1;2 gene is expressed mainly in roots, and accumulation of transcripts increases during sulfate deprivation. Examination of transgenic plants containing the Sultr1;2 promoter fused to the GUS-reporter gene indicates that Sultr1;2 is expressed mainly in the root cortex, the root tip and lateral roots. Weaker expression of the reporter gene was observed in hydathodes, guard cells and auxiliary buds of leaves, and in anthers and the basal parts of flowers. The results indicate that Sultr1;2 is primarily involved in importing sulfate from the environment into the root.

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