2.5 Leaf Metabolites
The metabolomic profiles for 211 genotypes of Family 52-124 were determined for leaves (leaf plastochron index 7 ± 2) sampled on September 14, 2006 at a USDA-FS field site near Grand Rapids, MI from plants in their first growing season in the field. Leaves were quickly collected and flash-frozen on dry ice, prior to shipping back to Oak Ridge National Laboratory, where ~200 mg fresh weight per sample were extracted in 80% ethanol (aqueous), as described in Zhao et al. , (2010) and analyzed for the major aromatic metabolites following trimethylsilylation and analysis by gas chromatography-mass spectrometry (GC-MS) using electron impact ionization (70 eV). The analytical and data extraction protocols were similar to that reported previously in Weston et al. , (2015). The major phenolic metabolites quantified included salicortin, α-salicyloylsalicin, salicyl-salicylic acid-2-O-glucoside, salirepin (gentisyl alcohol 2-O-glucoside), gentisic acid 5-O-glucoside, 1,2,4-benzenetriol, and gentisyl alcohol 5-O-glucoside.