ABSTRACT In many plant species, tolerance to toxic metals is highly dependent on glutathione, an essential metabolite for cellular detoxification. We evaluated the responses of glutathione metabolism to arsenite (AsIII) in Salvinia molesta, an aquatic fern that has unexplored phytoremediation potential. Plants were exposed to different AsIII concentrations in nutrient solution for 24 h. AsIII caused cell membrane damage to submerged leaves, indicating oxidative stress. There was an increase in the glutathione content and ϒ-glutamylcysteine synthetase enzyme activity in the submerged and floating leaves. The glutathione peroxidase and glutathione sulfotransferase enzymes also showed increased activity in both plant parts, whereas glutathione reductase only showed increased activity in the submerged leaves. These findings suggest an important role for glutathione in the protection of S. molesta against the toxic effects of AsIII, with more effective tolerance responses in the floating leaves.

A mirmecocoria é importante processo para a dinâmica vegetacional em diferentes ecossistemas, principalmente na região neotropical. Entretanto, a relação entre formigas e diásporos não mirmecocóricos é pouco documentada em ambientes da América do Sul. Dessa forma, este estudo teve por objetivos quantificar a taxa de remoção de diásporos não mirmecocóricos em fragmento de Cerrado e verificar se a presença de recursos energéticos e, ou, a abundância dos diásporos são determinantes para sua remoção por formigas. Formigas removeram 19,81% dos diásporos não mirmecocóricos coletados, e a presença de recursos energéticos influenciou significativamente essa remoção, não sendo significativa a relação entre abundância e remoção. Como a maioria dos diásporos coletados não era do tipo carnoso, com pouco ou nenhum recurso energético disponível para formigas, a importância da mirmecofauna para a remoção de diásporos não mirmecocóricos pode estar sendo subestimada.

The myrmecochory is an important process for the vegetation dynamic in different ecosystems, especially in the neotropics. However, the relationship between ants and non myrmecochorus diaspores is sparsely documented for environments of South America. Thus, this study aimed to quantify the removal rate of non myrmecochorus diaspores by ants in a Cerrado remnant and the influence of energy source presence or its abundance in diaspores for ant removal chance. Ant fauna removed 19.81% of non myrmecochorus diaspores collected and the presence of energy resources determines their removal, not being a significant relationship between abundance and removal. Since most diaspores collected were not fleshy, with few or none available energy resources for ants, the importance of ant fauna for diaspores removal of non myrmecochocorus may have been underestimated.