Ricinus communis responses to exposure to potentially toxic metals: a NMR-based metabolomics approach

Soils contaminated with potentially toxic metals (PTM) may threaten Ricinus communis optimal growth and development, compromising yield and productivity. In this context, metabolomics may provide pivotal insights into the effect of PTM by mapping stress-induced metabolic shifts. Herein, we assessed the effect of exposure of R. communis young seedlings to cadmium (Cd) and lead (Pb) through physiological, biochemical, and metabolomics analyses. Exposure to Cd and Pb had the greatest impact on the root length (up to 69 % for Cd at 3.0 mM and up to 61 % for Pb at 3.0 mM) and dry weight (up to 51 % for Cd at 3.0 mM and up to 48 % for Pb at 1.5 mM) of the seedlings, whereas endosperm showed fewer variations. Furthermore, exposure to Cd and Pb impacted the content of carotenoids and chlorophyll a and of the young seedlings. Compared to the control condition, exposure to Cd and Pb has reduced superoxide dismutase (SOD) activity in all tissues. Thirty metabolites were identified by Nuclear Magnetic Resonance (NMR), including amino acids, organic acids, amines, carbohydrates, and lipids. Partial Least Squares Discriminant Analysis (PLS-DA) revealed tissue-specific metabolic signatures in response to exposure to Cd and Pb, whereas the analysis of the Variable Importance in Projection (VIP) scores allowed the identification of key discriminators in Cd-stressed and Pb-stressed seedling tissues, highlighting tissue- and PTM-specific metabolic reprogramming. The data presented highlight Cd and Pb distinct physiological and biochemical impacts on R. communis seedlings.