Metabolomic Discrimination of Near Isogenic Low and High Phytate Soybean Seeds

Methodologies for untargeted metabolomic profiling using liquid chromatography-mass spectrometry (LC-MS) were developed and applied to lipid-depleted methanolic extracts of soybeans seeds obtained from four near isogenic soybean lines (NILs) that differed in phytate content. The four lines differed in mutations for genes encoding two highly homologous multi-drug resistant proteins (MRPs). The double mutant exhibited the low phytate/emergence phenotype whereas the other three NILs, namely the two single mutants and the wild type, did not. Lipid-depleted aqueous methanol extracts were analyzed by orthogonal chromatographic separations (reversed-phase and hydrophilic interaction) in both positive and negative ionization modes. Principal component analysis (PCA) of the LC-MS data clearly separated the low phytate line from the other three, with the major metabolite differences residing in the soyasaponin composition. Group A soyasaponins containing C22-terminated acetylated glucosides were of much lower concentration in the low phytate line, which favored terminally acetylated xyloside-based soyasaponins (soyasaponin A4, A5 and A6). Differing levels of the allergen Gly m 1 were also detected.