Alterações citológicas e no perfil proteico de sementes de feijão-de-corda (Vigna unguiculata) expostas ao glifosato

Abstract

In recent decades, the increasing use of pesticides in food production has caused contamination of living beings and accumulation in the biotic and abiotic segments of ecosystems, generating a series of disorders and changes in the environment. Thus, there is a great need to understand how these compounds interact with biological systems, in order to evaluate their effects on non-target organisms. Thus, this project aimed to evaluate the consequences of glyphosate (N-phosphonomethylglycine), the main herbicide used in Brazil, on the germination process of cowpeas (Vigna unguiculata). For this purpose, cowpeas seeds were incubated in different concentrations of glyphosate (1; 2.5; 5 and 10 mM) and in distilled water, as a negative control, to germinate. After the necessary period, the germination rate was evaluated and the values were expressed as the average. The results showed that seeds germinated at the highest concentration of glyphosate tested (10 mM) had a reduced germination rate, which decreased as the herbicide concentration was increased. The research continued with the control and treatments of 2.5 and 10 mM. In search of cytological changes, explants from different parts of the seedlings were subjected to routine histology and the slides obtained were viewed under an optical light microscope, in which the delayed development caused by exposure to glyphosate was observed. In addition, the seedlings obtained were subjected to protein extraction and analyzed by Mass Spectrometry, from which more than twenty underexpressed and overexpressed proteins related to stress responses and plant development were identified. Furthermore, oxidative stress tests - catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) - were performed to identify the antioxidant enzymes present, as well as their activity, which demonstrated a higher amount of CAT in the control group, associated with the natural development of the plant, a lower level of SOD in the treatment with 10 mM, which corroborates the reduction in growth observed, and similar results for all data obtained in the MDA test. The results demonstrate that glyphosate is capable of altering the germination of cowpea seeds, corroborating the hypothesis that the herbicide can affect non-target organisms both cytologically and in the protein profile.