Identification of Phenylglyoxal as a Flower-inducing Substance of Lemna from Pharbitis purpurea

Abstract

2-Hydroxy-l-phenyl-1,4-pentanedione (HPP) was isolated and identified from Pharbitis purpurea as a flower-inducing substance by using Lemna paucicostata 151 as a bioassay plant. This compound was racemic and was found to be an artifact, which could be formed by condensation between acetone and phenylglyoxal. Phenylglyoxal was shown to be naturally occurring in P. purpurea and also had flowering activity. The activity of each compound was inhibited by GA₃, ABA and IAA, and promoted by zeatin in L. paucicostata 151, as in the case of benzoic acid-related compounds.