Plantlets of two metallicolous and one nonmetallicolous populations of Biscutella laevigata subsp. laevigata were grown hydroponically for eight days at increasing concentrations of Tl: control, 1, 10 or 100 ppm Tl. Population tolerance to excess Tl was evaluated using a root elongation test. Tl concentration in shoots and roots was used as additional evaluation criteria. Based on the indicators used we confirmed the tolerance of population from Les Malines (F) (Lem) and demonstrate the tolerance of population from Cave del Predil (I) (Cap) and its capacity to accumulate Tl in shoots and roots (up to 28,745 mg kg-1 in shoots). Moreover the genetic structure was investigated using Amplified Fragment Length Polymorphism (AFLP) markers. All the results indicate that Cap population property of tolerance and accumulation of Tl is not a mere environmental effect but has also genotype bases and it is probably a constitutive and adaptive trait.
