Screening of Basidiomycetes and Ascomycetes for Plant Growth Regulating Substances. Introduction of the Gibberellic Acid Induced de-novo Synthesis of Hydrolytic Enzymes in Embryoless Seeds of Triticum aestivum as Test System

A new test system for the detection of plant growth regulating activities was successfully employed. In a screening for inhibitors of the gibberellic acid controlled synthesis of hydrolytic enzymes in embryoless wheat seeds (Triticum aestivum) 160 cultures of ascomycetes and basi­ diomycetes were tested. In the extracts of two cultures inhibitory activities were detected. From fermentations of a Hypholoma-species (basidiomycetes) 3,5-dichloro-4-methoxybenzyl alcohol \yas isolated as the active principle. Galiellalactone and two other new phytotoxins were isolated from cultures of the ascomycete Galiella rufa. At concentrations of 50 |ig/ml all four compounds inhibited the de-novo synthesis of a-amylases, proteases, and phosphatases. Further investigations on the mode of action revealed, that all four metabolites interfere with early steps of the biosynthetic path­ ways induced by gibberellic acids. In vivo, the germination of the seeds of several plants was inhibited by these compounds.