中文摘要：

利用气相色谱质谱联用技术（GC-MS）对东南景天根系分泌物进行近似全分析,采用代谢组学方法分析镉胁迫下两种生态型东南景天根系分泌物的差异,并探讨东南景天耐受或超富集镉的可能根际机制.收集0μmol·L~（-1）和40μmol·L~（-1）镉处理4 d后的超富集和非富集生态型东南景天根系分泌液,经冻干、甲醇洗脱、N-甲基-N-三甲基三氟乙酰胺（MSTFA）衍生化后进行GC-MS分析,共检测并定性出69个化合物.主成分分析（PCA）和正交偏最小二乘判别分析（OPLS-DA）结果表明,相同条件（镉处理水平、东南景天类型）下的样品能够明显地聚集在一起,不同条件下的样品能够显著的区分开来.运用OPLS-DA载荷图、模型的变量重要性因子和方差分析发现羟基乙酸、草酸、苯甲酸等18个根系分泌物质在4组间存在显著差异.它们的相对含量在不同处理条件间的变化趋势明显不同,表明东南景天可通过调节它们的分泌来耐受或超富集镉.

英文摘要：

Components of Sedum alfredii root exudates were surveyed by gas chromatography-mass spectrometry（GC-MS）. The variation of root exudates from two ecotypes of S.alfredii under Cd stress was explored by metabolomics analysis,and the probable effect mechanism of S.alfredii for tolerating or accumulating the heavy metal Cd was discussed. The root exudates were collected after 0 and40 μmol·L~（-1）Cd treatment for 4 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. Sixty-nine compounds were detected and identified. Principal component analysis（PCA） and orthogonal partial least-squares discrimination analysis（OPLS-DA） were carried out for pattern recognition and a clear separation among thedifferent treatments was achieved. Eighteen compounds which resulting in the separation among the different treatments were found and identified. The relative contents of these eighteen compounds varied under the different treatments. These results indicated that S. alfredii could be able to adjust the secretion of root exudates to tolerate or accumulate Cd.