Metabolomics for Biomarker Discovery: Key Signatory Metabolic Profiles for the Identification and Discrimination of Oat Cultivars

The first step in crop introduction-or breeding programmes-requires cultivar identification and characterisation. Rapid identification methods would therefore greatly improve registration, breeding, seed, trade and inspection processes. Metabolomics has proven to be indispensable in interrogating cellular biochemistry and phenotyping. Furthermore, metabolic fingerprints are chemical maps that can provide detailed insights into the molecular composition of a biological system under consideration. Here, metabolomics was applied to unravel differential metabolic profiles of various oat (Avena sativa) cultivars (Magnifico, Dunnart, Pallinup, Overberg and SWK001) and to identify signatory biomarkers for cultivar identification. The respective cultivars were grown under controlled conditions up to the 3-week maturity stage, and leaves and roots were harvested for each cultivar. Metabolites were extracted using 80% methanol, and extracts were analysed on an ultra-high performance liquid chromatography (UHPLC) system coupled to a quadrupole time-of-flight (qTOF) high-definition mass spectrometer analytical platform. The generated data were processed and analysed using multivariate statistical methods. Principal component analysis (PCA) models were computed for both leaf and root data, with PCA score plots indicating cultivar-related clustering of the samples and pointing to underlying differential metabolic profiles of these cultivars. Further multivariate analyses were performed to profile differential signatory markers, which included carboxylic acids, amino acids, fatty acids, phenolic compounds (hydroxycinnamic and hydroxybenzoic acids, and associated derivatives) and flavonoids, among the respective cultivars. Based on the key signatory metabolic markers, the cultivars were successfully distinguished from one another in profiles derived from both leaves and roots. The study demonstrates that metabolomics can be used as a rapid phenotyping tool for cultivar differentiation.

Phenolic compounds and biological activities of rye (Secale cereale L.) grains

The rye flour is, together with the wheat flour, the basic ingredient used in traditional bread baking. The rye grain contains many compounds with significant impacts on the consumer. Considering that, various biologically active phytochemicals were determined in extracts from mature grains of 19 rye genotypes (Secale cereale L.). The content of total phenols, flavonoids, phenolic acids and thiols, as well as antioxidant activities and inhibitory activities against trypsin, thrombin, and urokinase were analyzed by spectrophotometric methods. The vanillic acid, vanillin, p-coumaric acid, and t-ferulic acid were analyzed in particular by high performance liquid chromatography (HPLC). The observed differences in the amounts and activities between rye genotypes reflected variations in their genetic background. Rye grain is a remarkable source of specific phytochemicals. Genetic diversity in rye makes it possible to identify individual genotypes that have a unique content and biological activity of compounds deposited in mature grains. One subgroup of rye genotypes had higher values of antioxidant properties and concentrations of polyphenols. Other sub-group had higher proteinase inhibitory activities and contents of polyphenols. The third sub-group contained as though the universal genotypes, i.e. genotypes with average values in nearly all the measured parameters.