Cécile Nouet

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.

Chloroplastic and mitochondrial metal homeostasis.

Transition metal deficiency has a strong impact on the growth and survival of an organism. Indeed, transition metals, such as iron, copper, manganese and zinc, constitute essential cofactors for many key cellular functions. Both photosynthesis and respiration rely on metal cofactor-mediated electron transport chains. Chloroplasts and mitochondria are, therefore, organelles with high metal ion demand and represent essential components of the metal homeostasis network in photosynthetic cells. In this review, we describe the metal requirements of chloroplasts and mitochondria, the acclimation of their functions to metal deficiency and recent advances in our understanding of their contributions to cellular metal homeostasis, the control of the cellular redox status and the synthesis of metal cofactors.

Functional analysis of the three HMA4 copies of the metal hyperaccumulator Arabidopsis halleri

Highlight Expression of the Arabidopsis halleri hyperaccumulation gene HMA4 in A. thaliana reveals functional differentiation among the three AhHMA4 copies and non-polar localization of the AhHMA4 protein in root pericycle cells.

Zinc triggers a complex transcriptional and post-transcriptional regulation of the metal homeostasis gene FRD3 in Arabidopsis relatives

Highlight High expression of the FRD3 gene in the metal hyperaccumulator Arabidopsis halleri stems from complex zinc-regulated transcriptional and post-transcriptional mechanisms present in the non-hyperaccumulating Arabidopsis thaliana.