Metal hyperaccumulation: a model system for coevolutionary studies.

Recent years have seen a flurry of research activity concerning the hyperaccumulation of heavy metals by plants. Much of the interest in hyperaccumulation has been fueled by the commercial potential of phytoremediation, the use of plants to clean up contaminated soils (Baker et al., 1994; Salt et al., 1995; Chaney et al., 1997, 2000). These applications have in turn spurred many studies of the genetics and physiology of metal uptake (e.g. Krämer et al., 1996; Lasat et al., 1996; Salt & Krämer, 1999; Baker et al., 2000; see also Krämer, 2000; Lombi et al., 2000). Although phytoremediation provides an intriguing and potentially profitable backdrop, the ecology and evolution of hyperaccumulation in natural populations are interesting subjects in their own right. Two papers in this issue (Ghaderian et al., pp. 219-224; Davis & Boyd, pp. 211-217) are exciting contributions to the growing consensus that hyperaccumulation may act as a defense against herbivores and pathogens, and suggest that hyperaccumulation may become a model system for research in this area.