Abstract
Cadmium (Cd) is a harmful metal in the environment that readily enters the food chain when taken up by plants, thus posing a serious threat to human health. In this study, we conducted pot trials to investigate the effects of spermidine (Spd) and L-methionine (Met) on mitigation of Cd-induced toxicity in tomato (Solanum lycopersicum L. Mill.) by using physiological traits and inter-simple sequence repeat markers. The results showed that plants exposed to Cd had reduced photosynthetic pigments (chlorophyll a and b and carotenoids). Furthermore, the level of hydrogen peroxide (H2O2) was significantly increased by Cd exposure, which in turn elevated plant malondialdehyde and proline content and caused genotoxicity (increased DNA damage and reduced RNA synthesis). However, the application of Spd and Met was found to alleviate Cd toxicity in tomato plants by reducing the content of H2O2 and malondialdehyde, increasing the concentrations of chlorophyll a and b, carotenoids, and proline, and decreasing genotoxicity. Therefore, application of Spd and Met appears to enhance plant defense mechanisms against Cd toxicity and alleviates the negative effects of Cd stress in S. lycopersicum through modification of osmolytes.