Efeitos dos fungicidas à base de Tebuconazol e Difenoconazol na mitose de Lactuca sativa L. e Allium cepa L.

Abstract

The active principles of commercial fungicides from the triazole class – Tebuconazole (TBZ) and Diphenoconazole (DFZ) were detected in irregular amounts in food samples analyzed for the National Health Surveillance Agency (Anvisa), on The Program on Pesticide Residue Analysis (PARA). These substances are toxic for living beings, showing genotoxic, mutagenic and carcinogenic properties, even at low concentrations. In this context, it is important to elucidate the effects of these compounds as well as their toxicity mechanisms. In the present work the effects of TBZ- and DFZ-based fungicides were studie in to higher plant as model, Lactuca sativa L.e Allium cepaL., and the found results were divided in two works. The first oneobjectived to determine whether the changes in the mitotic cycle brought about by commercial fungicides containing the active principles TBZ and DFZ are related to the distribution pattern of histone H3 phosphorylation at serine 10 (H3S10ph) in chromosomes of meristematic cells of the plant model L. sativa. Mitotic cells were treated with commercial fungicides containing TBZ and DFZ and the results obtained were compared with a negative control (ultrapure water). Both fungicides were found to induce alterations in the distribution and number of signals of H3S10ph. The immune signal was considered irregular when scattered marks were observed throughout the chromosomes, or if such marks were absent and were found in cells contained sticky chromosomes, c-metaphases, anaphase bridges, and also in normal metaphases and anaphases. For the second, the objective was to understand how the immunolocalization of H3S10ph can help in understanding the alterations in the cell cycle, especially the aneugenic ones. Fungicides containing TBZ and DFZ as base active comppounds were used as inducing agent of aneugenic alterations. Aneugenic alterations as sticky chromosomes, c-metaphases, polyploidy and aneuploidy were observed and the majority of the cells that expressed these kind of alterations presented problems with the phosphorylation of H3S10ph. The results showed that the aneugenic events in meristematic cells of A. cepainduced by the commercial TBZ- and DFZ-based products can be explained by the epigenetic immuno-signal of H3S10ph.