Molecular mechanisms of metal hyperaccumulation in Arabidopsis halleri

Metal hyperaccumulation is one of the most remarkable adaptations evolved by plants to thrive on naturally metal-rich or anthropogenically contaminated soils. Among these species, the pseudometallophyte Arabidopsis halleri has emerged as a powerful model to unravel the molecular mechanisms underlying extreme Zn and Cd hypertolerance and hyperaccumulation. In this seminar, I will present how our research on A. halleri has evolved over the past two decades. I will first describe our initial efforts to identify and functionally characterize key genes controlling Zn and Cd transport and homeostasis, including HMA4 and FRD3, which helped establish the genetic basis of metal hyperaccumulation. I will then show how studies of natural variation among A. halleri populations revealed extensive diversity in metal accumulation and tolerance, highlighting the contribution of metal transport, cell wall properties and specialized metabolism to adaptive variation. Finally, I will present our most recent work dissecting cell-type-specific Zn and Cd transport pathways and regulatory networks in roots of contrasting A. halleri populations. Together, these studies illustrate how combining molecular genetics, natural diversity and multi-omics provides an increasingly integrated view of the processes that enable plants to adapt to extreme environments, while offering new perspectives for crop improvement and the sustainable management of metal-contaminated soils.