||NonprocessedMS data from GC-TOFMS analysis were exported in NetCDF format generated by chromatography processing and mass spectral deconvolution software, Leco ChromaTOF version 3.22 (LECO, St. Joseph, MI, USA) to MATLAB 7.0 (Mathworks, Natick, MA, USA), where all data pretreatment procedures, such as smoothing, alignment, time-window setting and H-MCR were carried out. The resolved mass spectra were matched against reference mass spectra using the NIST mass spectral search program for the NIST/EPA/NIH mass spectral library (version 2.0) and our custom software for peak annotation written in Java. Peaks were identified or annotated based on RIs and the reference mass spectra comparison from the Golm Metabolome Database (GMD,http://csbdb.mpimpgolm.mpg.de/csbdb/gmd/msri/gmd_msri.html) released from CSB.DB and our in-house spectral library. The metabolites were identified and defined as annotated metabolites by comparison with RIs from the library databases (GMD and our own library) and with those of authentic standards and mass spectra from these two libraries. Data were normalized using the CCMN algorithm and metabolite identifiers were organized using MetMask.