Metabolomic Analysis of Barley by Gas Chromatography/Mass Spectrometry

Climate change increases drought risk to agriculture and impacts both food nutrient content and overall food security. Metabolomics is one way to observe and quantify the impacts of drought on grain and other agricultural products. The identified metabolites may allow for the identification of the biochemical response that allows the plant to tolerate stressful environments. The methodology presented herein allowed for the total metabolomic analysis of barley flour using gas chromatography/mass spectrometry (GC/MS). Barley flour metabolite extracts were fractionated into four fractions based on polarity. To allow for analysis by GC/MS, metabolites were derivatized to increase volatility and metabolite separation: fatty acids esters were derivatized into fatty acid methyl esters; sugars were oximated into their straight chain form; and metabolites with hydroxyl groups were converted to their corresponding silyl ethers. The derivatized samples were injected into the GC/MS and the generated mass spectra were used for metabolite identification by comparing the generated spectra to the National Institute of Standards and Technology (NIST) Tandem Mass Spectra library. The method described here can also be used to examine the total metabolome for other plants, furthering our understanding of the biochemical responses of stressed plants.