Cadmium stress alters the essential oil composition and the expression of genes involved in their synthesis in peppermint (Mentha piperita L.)

Abstract Cadmium (Cd) is one of the heavy metals whose presence in soil induces oxidative stress in plants. This investigation was conducted to determine the modifications in some biochemical traits of peppermint (Mentha piperita L.) under cadmium stress. Likewise, the expression of key genes involved in the biosynthesis of menthol and menthofuran, two significant components of peppermint’s essential oil, was measured. The expression of peppermint genes under cadmium stress was measured for the first time in this research. The chemical composition of its essential oil, that makes peppermint a valuable herb, was also analyzed to determine the content of the principal constituents. Menthol content dropped, and menthofuran and pulegone concentrations increased by augmenting Cd. Increasing Cd level in the soil was followed by a reduction in the expression of MR (menthone reductase) and PR (pulegone reductase) genes, while an increase in the expression of MFS (menthofuran synthase) was observed. Assessment of differences in some biochemical traits was performed additionally. Malondialdehyde, hydrogen peroxide and proline contents dilated along with the antioxidant capacity. The total protein content decreased, while peppermint responded to Cd stress by increased activity of catalase, ascorbate peroxidase and polyphenol oxidase enzymes.