Abstract
This chapter reviews the genetic variation in selenium (Se) accumulation between plant species and the genetic variation in Se accumulation that occurs within plant species. Although selenium is an essential element for many prokaryotes, archaebacteria and eukaryotes, it is not required by either fungi or higher plants. In addition to variation in the ability of different species to accumulate Se, there is considerable variation in tissue Se concentration among genotypes of a species growing in the same environment. Plant species that hyperaccumulate Se include members of the Amaranthaceae, Asteraceae, Brassicaceae, Fabaceae, Orobanchaceae and Rubiaceae. There is considerable genetic variation in the ability to tolerate and accumulate Se in tissues both among and within plant species. Differences in Se metabolism underlie the contrasting abilities of plant species to tolerate and accumulate Se in their tissues and led to the evolution of the seleniferous flora.