ABSTRACT
A metabonomics method based on gas chromatography_mass spectrometry ( GC_MS) was developed for detecting the significant differences of root exudates of the Cd hyperaccumulator Sedum alfredii under different treatments and study the effect mechanism of S. alfredii tolerating or accumulating the heavy metal Cd. The root exudates were collected after treatment for 4 and 8 days with 0 and 40μmol/L Cd. The collected solution was lyophilized and dissolved with methanol, and after derivatization with methoxyamine hydrochloride and N_methyl_N_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 separation among the different treatments was achieved. Twelve compounds which caused the separation among the different treatments were found and identified. With the change of treatments, the relative amount of these 12 compounds revealed different trends, which indicated that the Cd hyperaccumulator S. alfredii could adjust the secretion of root exudates to tolerate or accumulate the heavy metal Cd.