Metabolic profiling of Citrus maxima L. seedlings in response to cadmium stress using UPLC-QTOF-MS

Cadmium (Cd) pollution significantly reduces agricultural crop yields. In our research, metabolomic changes in Citrus maxima L. subjected to Cd stress were investigated using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) in tandem with multivariate analytical techniques. This integrative method, coupled with physiological evaluations, aimed to elucidate the core adaptive mechanisms to Cd stress. We found that under Cd stress, C. maxima seedlings exhibited elevated levels of reactive oxygen species, malondialdehyde, and electrolyte leakage. Furthermore, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) demonstrated distinct a separation of the metabolome among the different treatment groups under Cd stress, indicating dynamic metabolic changes. Metabolic analysis suggested that genes involved are initially induced by Cd treatment, followed by the activation of the flavonoid biosynthesis pathway. This investigation provides new insights into the complex metabolic responses of C. maxima seedlings to Cd exposure.