RELATIONSHIPS BETWEEN THE STRUCTURE AND THE PHYTOTOXICITY OF THE FUNGAL TOXIN TENUAZONIC ACID

Article abstract of DOI:10.1016/0031-9422(88)80594-6

Tenuazonic acid (3-acetyl 5-sec-butyl pyrrolidine-2,4-dione) is a metabolite produced by the fungal pathogen of rice Pyricularia oryzae.It inhibits growth of plants by interferring with protein synthesis at the ribosome level.We have synthesized analogues of tenuazonic acid with various substituents at C-3 and C-5.Substituents at C-5 other than sec-butyl or n-propyl, decrease the phytotoxicity of the analogues.But substitutions at C-3 abolish the toxicity.Thus, tenuazonic acid seems to have the optimal structure for phytotoxicity.Tenuazonic acid induces rice leaf defence reactions (browning) of reactive varieties which are resistant to P. oryzae.Some of the analogues synthesized have a low level of phytotoxicity and are able to induce this leaf browning of the reactive rice varieties.Thus different structural features are required for phytotoxicity and for leaf browning.Key Word Index - Tenuazonic acid; pyrrolidine-2,4-diones; rice; phytotoxicity; Pyricularia oryzae; structure-activity.