Evolutionary traits of heavy metal allocation and tolerance in sensitive and tolerant populations of Biscutella laevigata from southern Poland

Elevated heavy metal concentrations in the soil are a frequent consequence of past or ongoing industrial activities and they can impair plant establishment and growth. Tolerance to elevated concentrations of heavy metals has been developed by a small number of species which also form model systems to study evolutionary processes of adaptation to metal-contaminated environments. Hence, Biscutella laevigata, an herbaceous plant species related to several metal hyperaccumulators, is found in metalliferous as well as non-metalliferous sites of southern Poland but, by contrast with other members of the Brassicaceae family, has been so far little investigated. The principal objective in this project is to characterize mechanistic aspects of metal accumulation and tolerance and relate it to the genetic structure of populations of Biscutella laevigata with varying genotypes, phenotypes, metal accumulation and tolerance. Using seeds harvested at either uncontaminated mountain or metal-polluted lowland sites in southern Poland, phenotyping experiments are conducted in hydroponic and controlled conditions applying different levels of Zn concentrations and for durations predetermined, as to obtain differentiated phenotypic expression between genotypes. Zn allocation and compartmentation is measured using a histochemical test and confocal laser scanning microscopy. Results are compared with nutrient and metal concentrations within plant and soil samples from the donor sites. In a next step, the Zn allocation measurements are repeated using foliar material directly sampled from plants growing at the metal-polluted sites. Results are evaluated in the context of the site and plant evolutionary history, reclamation processes by the native vegetation and soil evolution. They should provide innovative insights on the metal homeostasis processes selected by plant evolution under the constrain of extreme and changing environmental conditions.