Multidimensional approach to evaluate Limonium brasiliense as source of early biomarkers for lead pollution monitoring under different saline conditions

The search for early indicators of stress (biomarkers) with low cost of determination (both economic and logistic) is a prominent issue in environmental studies. Consequently, an experimental study was conducted with the aim of validating the leaf shape variations as an early biomarker in plants growing in contaminated soils. We manipulated the Pb (0, 45 and 90 mu M) and salt (0 and 598 mM NaCl) concentrations to evaluate their accumulation pattern, and their effect in biomass, leaf shape, photosynthetic pigments, phenolic contents, antioxidant enzyme activities, and lipid peroxidation in Limonium brasiliense. Results showed that growth and chlorophylls pigments synthesis in L. brasiliense are mainly impacted by Pb rise. Furthermore, the activities of the antioxidant enzymes and the lipid peroxidation both were increased by the Pb and salt addition; whereas phenolic content appeared to be more sensitive to salinity rise. On the other hand, changes in leaf shape were induced with Pb principally, and salt rise. The plants growing under stress conditions (Pb and salt treatments) showed expanded petioles and lanceolate limbos. Pb concentrations were always higher in roots than in aerial structures, suggesting that L. brasiliense could be a good candidate to the phytostabilization of Pb in polluted soils. The agreement in the changes of the several response variables measured as a product of the manipulated stressful factors suggests that L. brasiliense is a suitable bioindicator and their phenotypic plasticity is an early biomarker of stress by contamination. Leaf shape resulted to be a useful, practical and low-cost biomarker of stress on plants growing on polluted environmental conditions.