Metabolic profiling analysis of root exudates from the Cd hyperaccumulator Sedum alfredii under different Cd exposure concentrations and times

Abstract

Components of the Cd hyperaccumulator Sedum alfredii root exudates were analyzed by gas chromatography-mass spectrometry (GC-MS), the variation of the root exudates from S. alfredii under different Cd exposure concentrations and times was explored by metabolomics analysis, and the probably effective mechanism of S. alfredii for tolerating or accumulating the heavy metal Cd was discussed. The root exudates were collected after being treated with 0, 5 and 10 μmol L⁻¹ Cd for 4 and 8 days. The collected solution was lyophilized and eluted with methanol; after derivatization with methoxyamine hydrochloride and N-methyl-N-(trimethylsilyl) trifluoroacetamide, the samples were analyzed by GC-MS. Principal component analysis (PCA) and orthogonal partial least-squares discrimination analysis (OPLS-DA) were carried out for pattern recognition, and a clear difference in the root extract content was achieved when using the different treatments. 15 compounds, responsible for the differentiation between the root extracts when using the different treatments, were found and identified. The changing tendencies in the relative content of these 15 compounds under the different treatments were explored. These results indicated that the Cd hyperaccumulator S. alfredii could be able to adjust the secretion of root exudates to tolerate or accumulate the heavy metal Cd.