Differentiation of four varieties of germinating Thai colored indica rice (Oryza sativa L.) by metabolite profiling

Abstract

A comparative metabolite profiling procedure was applied to differentiate four different Thai colored indica rice (Oryza sativa L.), including Hom Daeng (red), Rice Berry (purple), Hom Nin (black) and Hom Mali 105 (non-colored) over the course of germination. The samples taken during germination at 28 - 30° with 90 -95% relative humidity for a total of 48 h were subjected to an extraction and fractionation procedure, covering a wide spectrum of lipophilic and hydrophilic low molecular weight constituents. A clear differentiation by principal component analysis indicated that all samples represented similar pattern direction along PC1 according to metabolic changes during the germination process. A differentiation at every stage of germination was observed along PC2 for each of the varieties of colored rice. Relative quantifications of selected metabolites exhibited dynamic changes in the metabolites at different germination stages. Thai black and purple rice contained higher levels of metabolites than the red and colorless samples.