Genotypes of the aquatic plant Myriophyllum spicatum with different growth strategies show contrasting sensitivities to copper contamination

Eva Roubeau Dumont (1) , Camille Larue (1) , Hiram Castillo-Michel (2) , Hervé Gryta (3) , Clarisse Liné (1) , David Baqué (1) , Elisabeth Maria Gross (4) , Arnaud Elger (1)

1 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement
2 ESRF - European Synchrotron Radiation Facility
3 EDB - Evolution et Diversité Biologique
4 LIEC - Laboratoire Interdisciplinaire des Environnements Continentaux

Genotypic variability has been considered for years as a key attribute in species adaptation to new environments. Extensive research on mechanisms of chemical resistance has been conducted for agriculture and weed management purposes, but genotypic variability remains poorly studied in response to chemical exposure in a context of global change. As aquatic ecosystems are particularly affected by environmental changes, we aimed to study how genotypic variability could inflect the sensitivity of aquatic plants to chemicals. Seven genotypes of Myriophyllum spicatum were exposed to three copper concentrations at 0, 0.15 and 0.5 mg/L, and actual exposure concentrations were monitored. The sensitivity of the different genotypes was assessed through several endpoints such as relative growth rate (RGR) and root and lateral shoot production, as well as physiological markers, such as plant biomacromolecular composition. Our results showed that genotypes exhibited significant differences in their life-history traits in absence of chemical contamination. Some life-history trait syndromes were observed, and three growth strategies were identified: (1) biomass production and main shoot elongation, (2) dry matter storage with denser whorls to promote resource conservation and (3) lateral shoot production. An up to eightfold difference in sensitivity for growth-related endpoints was observed among genotypes at low Cu concentration (0.15 mg/L). Co-inertia analysis revealed that genotypeDifferences in sensitivity were partially attributed to morphological life-history traits explained 62% of the total variation in sensitivity to Cu. Our results confirm that genotypic variability can significantly affect M. spicatum sensitivity to Cu, and may influence the outcomes of laboratory testing based on the study of one single genotype. We therefore recommend including genotypic variation as an assessment factor in ecological risk assessment and to study this source of variability more in depth as a possible driver of ecosystem resilience.

Domaines: Sciences de l'environnement

Eva Roubeau Dumont, Camille Larue, Hiram Castillo-Michel, Hervé Gryta, Clarisse Liné, et al.. Genotypes of the aquatic plant Myriophyllum spicatum with different growth strategies show contrasting sensitivities to copper contamination. Chemosphere, 2020, 245, pp.125552. ⟨10.1016/j.chemosphere.2019.125552⟩. ⟨hal-02997840⟩