Integrated metabolomic and transcriptomic profiling revealed coping mechanisms of the edible and medicinal homologous plant Plantago asiatica L. cadmium resistance

Abstract

Abstract Rapidly increasing cadmium (Cd) pollution led to the increase in contamination in farmland. The study explained the Cd resistance mechanisms of Plantago asiatica L. via physiological, metabolomic, and transcriptomic analyses. The results showed that as soil Cd level increased, proline content declined and then increased significantly. In contrast to the H2O2 content change trend, contents of soluble protein and malondialdehyde (MDA) first decreased, then increased, and finally, declined. Leaf Cd concentration was positively related to soluble protein content and negatively to both MDA content and activities of superoxide dismutase (SOD) and catalase (CAT). Most of the top 50 differential metabolites belonged to organic acids and sugars. Besides combining metabolome and transcriptome data, in the metabolic network involving the target metabolic pathways (e.g., ascorbate and aldarate metabolism, glutathione metabolism, galactose metabolism, and glyoxylate and dicarboxylate metabolism), dehydroascorbate (DHA), regulated by l-ascorbate peroxidase (APX) and l-gulonolactone oxidase (GULO), was significantly up-regulated. This illuminated that, in P. asiatica, CAT and SOD played vital roles in Cd resistance, and soluble protein and MDA acted as the main indexes to characterize Cd damage. It also suggested that DHA functioned effectively in Cd resistance, and the function was regulated by APX and GULO.