Biology and Fertility of Soils

, Volume 11, Issue 3, pp 203-209

First online:

Broad antifungal activity of β-isoxazolinonyl-alanine, a non-protein amino acid from roots of pea (Pisum sativum L.) seedlings

  • S. U. SchenkAffiliated withFachbereich Biologie, Botanisches Institut, Philipps-Universität Marburg
  • , F. LambeinAffiliated withLaboratory of Physiological Chemistry, State University of Gent
  • , D. WernerAffiliated withFachbereich Biologie, Botanisches Institut, Philipps-Universität Marburg

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β-(Isoxazolin-5-on-2-yl)-alanine (βIA), a heterocyclic non-protein amino acid from root extracts and root exudates of pea seedlings, acts as a potent growth inhibitor of several eukaryotic organisms, including yeasts, phytopathogenic fungi, unicellular green algae, and higher plants. The antibiotic effect on baker's yeast was reversed by l-methionine, l-cysteine, and l-homocysteine. Phytopathogenic fungi such as Botrytis cinerea, Pythium ultimum, and Rhizoctonia solani grown on agar containing βIA were inhibited in the growth of mycelia or in the production of sclerotia. In contrast, no significant inhibition of either Gram-positive or Gram-negative bacteria was observed. Rhizobium leguminosarum, the compatible microsymbiont of Pisum spp., and Rhizobium meliloti were able to tolerate up to 2.9 mM βIA (500 ppm) without any effect on the growth rate. Bradyrhizobium japonicum even gave a positive chemotactic response to βIA. The ecological significance of βIA as a preformed plant protectant during the seedling stage of Pisum spp. and other βIA-containing legumes is discussed.

Key words

Antifungal activity Saccharomyces cerevisiae Phytopathogenic fungi Heterocyclic non-protein amino acid Pisum sativum Constitutive plant defence