Bioorganic chemistry of infection-inducing substances produced by phytopathogenic fungi.

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ObjectivePathogenic action of microbes on plants are often highly host-specific. Not in many instances the mode of this specific action had been given chemical and biological basis, but some of the cases have been attributed to the production of host determinants (infection-inducing substances) such as host-specific toxic products (HST) by the microbes. In the presently proposed work the subjects of study are a) isolation and structure determination of ACTG-toxin and HV-toxin related components produced by the fungi A. citri and H. victoriae, which cause epidemic brown spot disease of Dancy tangerine and Victoria blight disease of oat, respectively, b) disease of Dancy tangerine or study of structure-bioactivity relationship of HMT- and PM-toxins produced by the fungi H. maydis, race T and Phyllosticta maydis, respectively, which cause epidemic blight-disease on the same species of corn , c) preliminary examinations of the culture conditions and bioassay methods in order to isolate new infection-inducing substances from fungi, except known HST producing fungi, such as P. oryzae and H. maydis, race O.Resultsa) Two minor ACTG-toxin related compounds (ACTG-toxin G and H) and a new sesquiterpenoid, dihydrosporogen AO-1, have been isolated and their structures have been determined. Structure of HV-toxin M was determined as a new victorin C related compound and HV-toxin H was identified with victorin C. Isolation of the other minor components of HV-toxin are in progress.b) Thirty nine of HMT- and PM-toxin mimics have been systematically synthesized. Comparison of their biological activities suggested that bioactive conformations of HMT- and PM-toxins are certain cyclic forms.c) Preliminary examination& of infection-inducing substances from P. oryzae and H. maydis, race 0 are in progress.