Kenaf Phytoalexin: Toxicity Of O-Hibiscanone And Its Hydroquinone To The Plant Pathogens Verticillium Dahliae And Fusarium Oxysporum F. Sp. Vasinfectum

o-Hibiscanone (HBQ) is a phytoalexin produced by kenafin response to infection by the wilt pathogen Verticillium dahliae. In several bioassays utilizing both conidia and mycelia of V. dahliae, HBQ was significantly more toxic than desoxyhemigossypol, the most; potent phytoalexin produced by cotton. HBQ also was more toxic to conidia of Fusarium oxysporum f, sp. vasinfectum. C-13-NMR experiments revealed that HBQ is reduced to its hydroquinone by V. dahliae conidia. Bioassays of HBQ and its hydroquinone established that the quinone is considerably more toxic to V. dahliae than is the hydroquinone. This biotransformation apparently represents a detoxification mechanism employed by the pathogen.