Effects of micro(nano)plastics on stem xylem embolism resistance in a woody angiosperm under drought

• Applicant: Dr. Lucian Kaack
• Subject Area: Evolution and Systematics of Plants and Fungi ; Plant Biochemistry and Biophysics ; Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 567607608

Micro(nano)plastics (MNPs) are emerging pollutants that accumulate in terrestrial ecosystems and pose potential risks to plant hydraulic function. In vascular plants, water is transported through xylem conduits under significant negative pressures, that can be disrupted by the formation of gas emboli. The entry of MNPs with hydrophobic surfaces into the xylem may lower the threshold for cavitation, thereby facilitating embolism formation and compromising water transport under drought stress. Although previous studies have documented the uptake and vascular translocation of MNPs in plants, their direct impact on xylem embolism resistance remains largely unexplored. The primary goal of this pilot study is to provide proof of principle regarding the potential direct risk that MNPs pose to the plant water transport. We hypothesize that hydrophobic MNPs, upon entering the xylem, act as nucleation sites for gas bubble formation, thereby reducing the threshold for cavitation initiation and increasing plant vulnerability to drought-induced hydraulic failure. Through an interdisciplinary approach that combines physiological experiments, high-resolution imaging (including fluorescence, confocal and electron microscopy), and molecular simulations, we aim to elucidate whether and how MNPs with their hydrophobic surfaces influence cavitation dynamics within xylem conduits and embolism formation at less negative pressures, increasing plant vulnerability to drought-induced hydraulic failure. The experimental design employs hydroponic and potted soil setups using Fagus sylvatica as the model species. Saplings will be exposed to different concentrations of fluorescently labeled 0.05 μm polystyrene nanoparticles. The uptake into the xylem will be explored microscopically. Differences in stem xylem embolism resistance will be compared by measurements to construct vulnerability curves. To elucidate the mechanisms underlying the effects of MNPs on cavitation dynamics, we will conduct classical all-atom molecular dynamics simulations, focusing on the different interfaces. Additional pre-tests will be conducted to complement the main experiments and explore cost-efficient, larger-scale approaches using self-produced MNPs. Understanding these mechanisms is critical in the context of global climate change, where increasing drought frequency threatens agricultural productivity and forest resilience. If MNPs indeed reduce embolism resistance, their environmental accumulation could represent an additional stressor contributing to plant decline and ecosystem shifts. This research will help assess the long-term ecological risks of MNP pollution and inform sustainable management practices. By bridging plant physiology and simulations, our findings will provide a scientific basis for evaluating MNPs as potential contributors to global change factors, emphasizing the need for interdisciplinary approaches to environmental sustainability.

• DFG Programme: WBP Position