Prospecção da toxicidade e atividade enzimática de fungicidas por meio de bioensaios com Lactuca sativa

• Autor(a) principal: Aragão, Francielen Barroso
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/9936
• topic: Citogenotoxicity; Plant comet assay; Fungicides; Oxidative stress; Root growth; Citogenotoxicidade; Cometa; Estresse oxidativo; Crescimento radicular; TUNEL; Agronomia; Fungicidas; Mutagênese; Enzimas; Alface; 57

The increase in food demand due to world population growth, results in increased use of synthetic substances in order to increase food productivity. However, the growing advance of monoculture stands out for significant volume of waste dispersed in environment, such as pesticides. These substances cause environmental impacts, because when leached can affect groundwater and surface water, damaging micro and macro local biota. Thus, the search for elucidation of hereditary or lethal effects of toxic substances in living organisms, various evaluation methods have been developed in order to understand the properties and mechanisms of action thereof. Therefore, the study aimed to evaluate the effect of tebuconazole fungicides (TBZ) and difenoconazole (DFZ) through different analysis tools in the plant model Lactuca sativa. Lactuca sativa the seeds were germinated in distilled water to achieve 1-2 mm, after reaching the minimum size were treated with different concentration of fungicides: TBZ (25; 50; 100; 200 e 400 g/mL) and DFZ (15,62; 31,25; 62,5; 125 e 250 g/mL). Trifluralin (0,84 g/L) and MMS (4x10-4 mol L-1 ) was used as a positive control (C +) and distilled water as a negative control (C-). Analysis of cytogenotoxic potential was performed through cell cycle analysis (mitotic index, chromosomal aberrations (CA) and nuclear aberration (NA), quantification of DNA damage by comet test and Tunnel test, as well as evaluation of oxidative stress through antioxidant enzymes quantification as: CAT, APX, SOD and POD. The means were submitted to ANOVA and compared by the Kruskal Wallis and Tukey tests (p <0.05). The different dilutions of TBZ and DFZ showed reduction in root growth compared to negative control. Compared with mitotic index of C-, the concentrations of DFZ showed no statistical difference, whereas the concentrations of TBZ showed a significant reduction in the concentration C1, and a significant increase in the other concentrations. However, both DFZ and TBZ showed a significant increase in CA in the highest concentrations. Both fungicides induced formation of CA as cmetaphases, bridges, and sticky chromosomes. The higher concentrations of the main principles increased the NA percentage. It was observed increased the DNA fragmentation evaluated by the comet and Tunel test in fungicide TBZ, and only for the TUNEL in the fungicide DFZ. Oxidative stress analysis showed that only the APX enzyme presented a statistical difference of C- for TBZ, whereas in DFZ only the SOD enzyme was statistically different from C-. Concerning to the tests carried out, it was observed that fungicides TBZ and DFZ were cytotoxic by reducing root growth, genotoxic by increasing the occurrence of NA and CA as well as increasing DNA fragmentation, and altered the enzymatic activity.