Chromium speciation modifies root exudation in two genotypes of Silene vulgaris

Abstract The extensive use of Cr compounds in industry has led to the disposal of this element in soil and water, with consequent hazards to the environment and human health. Phytomanagement of Cr contaminated sites could be a sustainable alternative to obtain a profit from otherwise useless land. The objective of this work was to evaluate the influence of Cr speciation on root exudation in two genotypes of the metallophyte Silene vulgaris , which have shown different tolerance to Cr(VI). Plant growth has been related to oxidative stress by malondialdehyde (MDA) measures. No toxicity symptoms were observed at the applied dose of Cr(III), whereas biomass was significantly reduced by exposure to Cr(VI). Shoots have been found to be more sensitive to Cr stress than roots. Cr accumulation in plants was correlated to exudate release rates and induced changes in their composition. The genotype SV21 showed less biomass reduction and oxidative stress than the less tolerant SV38. The increment of the exudation rate in the genotype SV21 under Cr(VI) exposure suggested that exudation could be one of the mechanisms implicated in the tolerance of this species.