Metal hyperaccumulation and hypertolerance: a model for plant evolutionary genomics

In the course of evolution, plants adapted to widely differing metal availabilities in soils and therefore represent an important source of natural variation of metal homeostasis networks. Research on plant metal homeostasis can thus provide insights into the functioning, regulation and adaptation of biological networks. Here, we describe major recent breakthroughs in the understanding of the genetic and molecular basis of metal hyperaccumulation and associated hypertolerance, a naturally selected complex trait which represents an extreme adaptation of the metal homeostasis network. Investigations in this field reveal further the molecular alterations underlying the evolution of natural phenotypic diversity and provide a highly relevant framework for comparative genomics.

► Metal hyperaccumulation and metal hypertolerance are adaptations involving alterations of the metal homeostasis network.
► Root-to-shoot metal transport represents a bottleneck for hyperaccumulation.
► Existing functions have been enhanced in metal hyperaccumulators.
► Gene copy number expansion and cis-regulatory mutations underlie the trait.
► The evolution of phenotypic diversity is being linked to molecular alterations.