Effects of cadmium on physiological characteristics and metabolic profiles of Salvia miltiorrhiza Bunge

The effects of cadmium (Cd) on the physiological indices and metabolomics of Salvia miltiorrhiza Bunge were investigated by pot experiments. Results showed that Cd stress significantly enhanced Cd, proline, and soluble protein content, decreased malondialdehyde (MDA) content (P < 0.05), increased catalase (CAT) activity, and inhibited peroxidase (POD) activity, with GSH contend and superoxide dismutase (SOD) activitivity showing no significant differences between the control and Cd stress group in S. miltiorrhiza roots. The metabolite profiles differed between the two groups, with 51 discriminating metabolites (mainly organic acids and amino acids) identified, which were mainly involved in amino acid and organic acid metabolism. The fold-change (FC) values of L-proline and L-histidine were greater than 2.5, and the FC values of 3,4,5-trimethoxybenzoic acid and rosmarinic acid were greater than 5, and they were the most up-regulated. There were significant positive correlations between Cd and the discriminating metabolites (especially amino acids and organic acids). These results revealed that S. miltiorrhiza accumulated a certain amount of Cd, and high levels of Cd stress led to peroxidation of membrane lipids, inhibition of antioxidant enzyme activities, and effects on the metabolomes of S. miltiorrhiza. Furthermore, S. miltiorrhiza resisted Cd stress mainly by regulating the metabolism of amino acids and organic acids, and up-regulating L-proline, L-histidine, 3,4,5-trimethoxybenzoic acid, and rosmarinic acid.