Several physiological, biochemical and molecular biology responses were analysed in Solanum nigrum L. plants exposed for 28 days to an effluent that resulted from the photo-Fenton treatment of a highly concentrated pesticide and systemic fungicide aqueous solution, containing metalaxyl as active compound (150mgL(-1)), in order to pinpoint metabolic steps for a future increase of these plants' capacity to deal with the chemical process by-products. Although plants suffered oxidative stress, as indicated by increased membrane damage and a negative effect on plant biomass, they absorbed the excess iron and acted on the resulting by-products present in the effluent after the photo-Fenton process. Nitrogen assimilation and metallothionein gene expression were down regulated, while glutathione biosynthesis increased. These results suggest an enhanced nitrogen assimilation and/or metallothionein accumulation as relevant key points for further plant improvement in order to increase the efficiency of this innovative strategy that considers integration of the photo-Fenton process (as chemical primary treatment) with S. nigrum L. plants (as biological remediation post-treatment) for heavily polluted wastewaters.
Keywords: Black nightshade; Gene expression; Glutamine synthetase; Metallothionein; Organic pollutants; Oxidative metabolism.
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