In Europe, a significant proportion of the population is overexposed to cadmium (Cd), a toxic metal present in plant foods such as cereals, tubers, leafy vegetables and chocolate. This cadmium comes from more or less polluted soil, where it is absorbed by the roots and distributed to the various parts of the plant. Predicting the Cd content in the crop produced on a given soil would enable us to better assess the risks of contamination in the food chain and adapt farming practices to reduce it.

Although we are beginning to correctly predict the total plant uptake of Cd, until now we have had no model for its distribution in the various organs, such as roots, stems, leaves or fruit. For this reason, the LSE, in association with LEMTA (UL-CNRS), has tested a thermodynamics-based formalism to simulate the accumulation of Cd in the different plant parts. This approach, which combines physics and plant physiology, postulates that the flow of Cd from one compartment of the plant to another is controlled by the difference in the chemical potential of the metal in each of these compartments. The equations relate the cadmium content of the nutrient solution to that of the roots, raw sap (in the xylem) and aerial tissues of the maize plant. They have enabled us to gain a better understanding of the metal distribution rules in the plant, by also taking into account the diffusion of the metal in the tissues and the movement of water due to transpiration by the plant.

To consolidate the model, it would be appropriate to extend the study by designing a growing system that would allow constant exposure of the roots to Cd over a longer period of time, taking into account the growth of the plant.

Contact : thibault.sterckeman@univ-lorraine.fr, Ingénieur de recherche LSE (UMR INRAE/UL)

Référence : Moyne C, Leglize P, Sterckeman T (2024). Using non-equilibrium thermodynamics to model cadmium accumulation by maize. Current Plant Biology 39: 100369. doi: https://doi.org/10.1016/j.cpb.2024.100369.