On the mechanism of genetic activity of dicarboximide, aromatic hydrocarbon and phenylpyrrole fungicides on diploid Aspergillus nidulans

Dicarboximide, aromatic hydrocarbon and phenylpyrrole fungicides increase significantly the frequency of mitotic segregation in diploid A. nidulans. They provide similar appearance, small sectors, of white and yellow recombination products. The analysis of iprodione induced mitotic recombinants, showed an increase of haploid and diploid segregants, but a considerable number of diploids were subchromosomal. Cytological observations at the light microscope level, showed that the normal stages of the mitotic process were appeared in presence of iprodione, as in the case of conidia germinating in fungicide-free medium. By the means of electron microscopy, nuclei with large openings in the nuclear membrane were observed. The damages of nuclear envelope, may result in disorganization of the spindle and make chromosomes susceptible to enzyme and/or free radicals attack.