Ecology and diversity of metal HYPERaccumulating species: integrating studies of gene expression, plasticity of accumulation, individual fitness, functional syndromes and complementary effects

• Applicants: Pierre Liancourt, Ph.D.; Professorin Dr. Katja Tielbörger
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems ; Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568846928

The ability of some plants to hyperaccumulate toxic metal(oid)s in their leaves is fascinating. Physiological studies revealed that this counterintuitive trait includes active absorption, translocation, detoxification and storage of metals. Clearly, for this trait to evolve, the fitness benefits have to outweigh direct (toxicity) and indirect costs (associated machinery). Assumed benefits include increased metal-tolerance, defense against enemies and competitors, or increased drought-tolerance. Unfortunately, physiologists and ecologists have mostly worked in isolation, on single species, and single metals limiting our ultimate understanding of ‘WHY’ hyperaccumulation has evolved. Here, we want to fill this gap by integrating studies on gene expression, metal allocation, individual fitness, functional trade-offs and community-level consequences of hyperaccumulation. We first ask ‘HOW’ plants hyperaccumulate metals using transcriptomics for several European hyperaccumulators and different metals, including, for the first time, Thallium (Tl). Gene expression will also be studied for functions presumably associated to hyperaccumulation, e.g. oxidative stress tolerance, enemy defense, photosynthetic capacity, and drought tolerance. We then ask whether hyperaccumulation increases WHEN specific stimuli occur (herbivory, competition, drought). This would suggest a key role of these stimuli in selection. Plastic response to the stimuli will be tested by measuring metal allocation in greenhouse experiments with three species hyperaccumulating Ni, Zn, Cd, and Tl. We then look at whether hyperaccumulation indeed deters herbivores or creates allelopathic effects. We then look at WHERE (soil types), for WHOM (plants with different hyperaccumulation ability) and under which circumstances fitness benefits outweigh costs by simultaneously studying hyperaccumulation, metal tolerance, herbivory, and their net effect on reproduction. In search for generality, we then use multi-species studies to compare functional traits of hyperaccumulators with those of coexisting, non-accumulating species. I.e., we ask ‘WHO’ meets the challenge of hyperaccumulation? E.g., acquisitive species, with high photosynthetic and metabolic rates, may better sustain this costly adaptation. Ecological strategies will be studied through functional trait measurements of 80 hyperaccumulating species (~ 10% of the world’s hyperaccumulators) and coexisting species across biomes and metal(oid)s (Ni, Zn, Cd, Tl, Se). Finally, we will scale up our findings to a community-level. We test for complementarity effects when hyperaccumulators grow WITH each other with rhizotron experiments (fine root interactions) and mesocosms (other interactions) to understand both community-level dynamics and ways for efficient for phytoremediation of contaminated soils.

• DFG Programme: Research Grants
• International Connection: France
• Co-Investigators: Privatdozentin Dr. Maria Májeková; Sara Tomiolo, Ph.D.
• Cooperation Partners: Professor Dr. Florian Delerue; Privatdozent Dr. Sylvain Merlot; Professor Dr. Maxime Pauwels; Professorin Dr. Catherine Sirguey