The wilty tomato mutants flacca and sitiens are impaired in the oxidation of ABA-aldehyde to ABA

Authors

  • I. B. TAYLOR,

    Corresponding author
    1. Department of Physiology and Environmental Science, University of Nottingham, School of Agriculture, Sutton Bonington, Leicestershire LE12 5RD, U.K.
      *Dr. I. B. Taylor, Department of Physiology and Environmental Science, University of Nottingham, School of Agriculture, Sutton Bonington, Leicestershire LE12 5RD, U.K.
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  • R. S. T. LINFORTH,

    1. Department of Physiology and Environmental Science, University of Nottingham, School of Agriculture, Sutton Bonington, Leicestershire LE12 5RD, U.K.
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  • R. J. AL-NAIEB,

    1. Department of Chemistry, University of Technology, Loughborough, Leicestershire, U.K.
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  • W. R. BOWMAN,

    1. Department of Chemistry, University of Technology, Loughborough, Leicestershire, U.K.
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  • B. A. MARPLES

    1. Department of Chemistry, University of Technology, Loughborough, Leicestershire, U.K.
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*Dr. I. B. Taylor, Department of Physiology and Environmental Science, University of Nottingham, School of Agriculture, Sutton Bonington, Leicestershire LE12 5RD, U.K.

Abstract

Abstract. Deuterium-labelled ABA-aldehyde was fed to various tomato genotypes. Normal and notabilis mutant plants incorporated substantial amounts of the label into ABA. In contrast, two ABA-deficient mutants, flacca and sitiens, reduced ABA-aldehyde to a mixture of cis- and trans-ABA alcohol rather than oxidizing it to ABA. It was concluded that ABA-aldehyde is the immediate precursor of ABA in higher plants. It appears that the flacca and sitiens lesions both act to block the last step of the ABA biosynthetic pathway. The mutant gene loci are likely to be involved in coding for different sub-units of the same dehydrogenase enzyme.

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