Glutathione (GSH) plays a central role in the plant tolerance against the toxic effects of metals. It is a key antioxidant and acts as a cofactor for glutathione S-transferase (GST). The main objective of this study was to determine the Pb tolerance and bioaccumulation by Dodonaea viscosa (L.) Jacq. and their relation to GSH production and GST activity. The relationship between the Pb tolerance and bioaccumulation by D. viscosa and the effect of the exposure time on the GSH production or the GST activity was assessed in trials with perlite under different Pb treatments. D. viscosa showed a remarkable tolerance to Pb [half-inhibitory concentration (IC₅₀) = 2,797 mg kg⁻¹] and accumulated up to 11,428 mg Pb kg⁻¹ in dry roots with a limited translocation to shoots without any signs of phytotoxicity after 105 days of exposure. The stress caused by the fast Pb uptake rate (489 mg kg⁻¹ day⁻¹) during the first 10 days of exposure was strongly correlated to increased GSH contents (~1.3-fold) and GST activities (~3.6-fold) in both shoots and roots. The results indicate that the Pb stress triggered a defense mechanism that involved increased contents of GSH and GST activities, suggesting that both variables are involved in the tolerance of D. viscosa against Pb toxicity.
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