Conversion of D-tryptophan to indole-3-acetic acid in coleoptiles of a normal and a semi-dwarf barley (Hordeum vulgare) strain |
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Authors: | Ken-ichi Tsurusaki Sachiko Watanabe Naoki Sakurai Susumu Kuraishi |
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Institution: | Dept of Environmental Studies, Faculty of Integrated Arts and Sciences, Hiroshima Univ., Hiroshima 730, Japan |
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Abstract: | Exogenously applied D-tryptophan (D-Trp) was more effective than L-Trp in inducing elongation of coleoptile segments of a normal barley ( Hordeum vulgare L. cv. Akashinriki) strain and a semi-dwarf strain with lower endogenous indole-3-acetic acid (IAA) level. D-cycloserine, an inhibitor of D-aminotransferase, completely inhibited both the D- and L-Trp-induced elongation of both strains. Addition of D-Trp increased IAA levels in both strains 4-fold over endogenous levels. The increase in IAA level was completely inhibited by D-cycloserine. The endogenous L-Trp level of semi-dwarf coleoptiles was similar to that of normal ones. These results suggested that IAA is synthesized by the conversion of L-Trp to indole-3-pyruvic acid via D-Trp in both strains, and that the lower IAA level of the semi-dwarf strain probably is a result of the impeded IAA biosynthesis involved in D-Trp. |
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Keywords: | Barley cycloserine dwarf D-tryptophan Hordeum vulgare HPLC indole-3-acetic acid |
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