Transporters in Arabidopsis roots mediating uptake of amino acids at naturally occurring concentrations

Authors

  • Henrik Svennerstam,

    1. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
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    • These two authors contributed equally to this work.

  • Sandra Jämtgård,

    1. Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
    2. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
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    • These two authors contributed equally to this work.

  • Iftikhar Ahmad,

    1. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
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  • Kerstin Huss-Danell,

    1. Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
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  • Torgny Näsholm,

    1. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
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  • Ulrika Ganeteg

    1. Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), SE-901 83 Umeå, Sweden
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Author for correspondence:
Ulrika Ganeteg
Tel: +46 90 786 84 31
Email: Ulrika.Ganeteg@genfys.slu.se

Summary

  • Recent studies of Arabidopsis have identified several transporters as being important for amino acid uptake.
  • We used Arabidopsis plants with altered expression of lysine histidine transporter 1 (LHT1), amino acid permease 1 (AAP1) and amino acid permease 5 (AAP5) with the aim of disentangling the roles of each transporter in the uptake of different amino acids at naturally occurring concentrations (2–50 μM).
  • LHT1 mutants displayed reduced uptake rates of l-Gln, l-Ala, l-Glu and l-Asp but not of l-Arg or l-Lys, while AAP5 mutants were affected in the uptake of l-Arg and l-Lys only. Double mutants (lht1aap5) exhibited reduced uptake of all tested amino acids. In the concentration range tested, AAP1 mutants did not display altered uptake rates for any of the studied amino acids. Expression analysis of amino acid transporter genes with important root functions revealed no major differences in the individual mutants other than for genes targeted for mutation.
  • We conclude that LHT1 and AAP5, but not AAP1, are crucial for amino acid uptake at concentrations typically found in soils. LHT1 and AAP5 displayed complementary affinity spectra, and no redundancy with respect to gene expression was found between the two transporters, suggesting these two transporters have separate roles in amino acid uptake.

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