Heavy metal stress induces adaptative responses in liverwort Conocephalum conicum L. (Dum.): an integrated biologic and metabolomic study

Plants undergo metabolic perturbations under various abiotic stress conditions: due to their sessile nature, the metabolic network of plants requires continuous reconfigurations in response to environmental stimuli to maintain homeostasis and combat stress.1 In this study, the adaptative responses of the liverwort Conocephalum conicum to the heavy metal stress was analysed through a multidisciplinary approach. The liverwort was in vitro growth reproducing the concentrations of heavy metals assessed in Sarno river (South Italy), representative of anthropogenically-impacted rivers in Europe. The biological responses considered, ROS production and localization, antioxidant enzymes, ultrastructural damage responded consistently with the expected environmental stress. In this study, an untargeted metabolomic method together with an ultra-high-performance liquid chromatography/electrospray ionization /tandem mass spectrometry (UHPLC/ESI-MS/MS) and molecular networking approach were used for the study of the differential production of secondary metabolites.2 This approach permitted a fast tentative annotation of several known and unknown metabolites. The metal stress tolerance toolkit in C. Conicum involved the production of flavonoid components as well as a remodelling of the lipid metabolism. The multidisciplinary roadmap proposed in the present study pave the way to future investigations aimed to further mining the secondary metabolome of plants, including those of medicinal and alimentary interest, when exposed to abiotic stress.