Uptake of glycine by field grown wheat

Authors

  • Torgny Näsholm,

    1. Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden;
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  • Kerstin Huss-Danell,

    1. Department of Agricultural Research for Northern Sweden, Crop Science Section, Swedish University of Agricultural Sciences, S-904 03 Umeå, Sweden;
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  • Peter Högberg

    1. Section of Soil Science, Department of Forest Ecology, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden
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Author for correspondence: Torgny Näsholm Tel: +46 90 786 6302 Fax: +46 90 786 5901 Email:torgny.nasholm@genfys.slu.se

Summary

  • • Uptake of glycine, a simple organic nitrogen (N) source, directly from the soil is shown here in a conventionally cropped wheat ( Triticum aestivum ) field.
  • • Wheat plants were harvested after tracer injections into the soil of two forms of dual-labelled amino acid; [ 13C2], [15N]-glycine and 2-[13C], [15N]-glycine. Uptake of intact amino acid was analysed by stable isotope–, and gas chromatography–, mass spectrometry.
  • • Significant increases in 13 C were found in root extracts for all glycine-treated plants. Regression analysis of excess 13 C vs excess 15 N for the two glycine forms showed that at least 20% of absorbed glycine-N was derived from uptake of intact glycine. Gas chromatography–mass spectrometry was used to verify the presence of intact dual-labelled glycine in wheat roots. Results also indicated that glycine decarboxylase had a minor role in metabolism of absorbed glycine in wheat roots. Microbial metabolism in the soil did, however, result in rapid decarboxylation of added glycine.
  • • Field-grown wheat takes up glycine directly from the soil; the dependence of agricultural plants on nitrate and ammonium as the only forms of available N is therefore questionable.

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