Arabidopsis thaliana as a Model System for Studying Lead Accumulation and Tolerance in Plants

In addition to the often-cited advantages of using Arabidopsis thaliana as a model system in plant biological research ( 1 ), Arabidopsis has many additional characteristics that make it an attractive experimental organism for studying lead (Pb) accumulation and tolerance in plants. These include its fortuitous familial relationship to many known metal hyperaccumulators (Brassicaceae), as well as similar Pb-accumulation patterns to most other plants. Using nutrient-agar plates, hydroponic culture, and Pb-contaminated soils as growth media, we found significant variation in Arabidopsis thaliana ecotypes in accumulation and tolerance of Pb. In addition, we have found that Pb accumulation is not obligatorily linked with Pb tolerance, suggesting that different genetic factors control these two processes. We also screened ethyl methanesulfonate-mutagenized M2 populations and identified several Pb-accumulating mutants. Current characterization of these mutants indicates that their phenotypes are likely due to alteration of general metal ion uptake or translocation processes since these mutants also accumulate many other metals in shoots. We expect that further characterization of the ecotypes and mutants will shed light on the basic genetic and physiological underpinnings of plant-based Pb remediation.