抄録
Sclerotinia fructicola, a pathogenic brown rot fungus of stone fruits, produced abundant asexual arthrospores when grown on an agar medium in darkness, whereas poorly or not at all under illumination of light. We found that the dark-induced sporulation of this fungus was attributed to production of sporogenic substances in the mycelia cultured in darkness. We now describe the isolation and structural elucidation of sporogenic substances produced by this fungus grown on an agar medium in darkness. 1) The major sporogenic substance, named sclerosporin, was a new fungal sesquiterpene (C_<15>H_<22>O_2) with a guaiane skeleton, inducing the sporulation at 0.001μg/ml, and its plain structure was elucidated as 1, using 180μg of the sample with the ultramicro-techniques. Two related metabolites, sclerosporal and sclerosporene, were isolated and their structures were determined as 3 and 4, respectively. 2) The minor active substance was identified as R-(-)-glycerol monolinolate (2) by synthesis. Interestingly, its antipodal S enantiomer did not show the sporogenic activity. 3) A new metabolite with sporogenic activity was produced in the submerged culture, although the sporulation did not occur under these conditions, and the compound was determined as dolichol-23.
