Grain size and shape reflects variability in metabolite and elemental composition in traditional rice varieties

Traditional rice varieties serve as a pool for diverse germplasm. Present study investigates the compositional variability of metabolites and elements in traditional rice varieties with varying grain size and shape. Grain quality characterization of traditional rice varieties including medium, small and bold shaped grain types was performed. Additionally, whether these differences in the size and shape of varieties are reflected in the metabolite and elemental composition of their grains was explored. Two major clusters were obtained from hierarchical clustering of varieties based on the similarities of grain size and shape. The second cluster was further separated into four sub-clusters (clusters II, III, IV and V). A single variety representative of each cluster was selected for further analysis. Metabolite analysis and elemental analysis of grains was carried out by gas chromatography mass spectrometry (GC–MS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. A total of 47 metabolites belonging to different metabolite groups and a total of 35 minerals were identified from dehulled grains of selected varieties. Distinct differences detected amongst the representative varieties from five clusters with respect to their metabolite and elemental profiles were further confirmed by partial least square discriminant analysis (PLS-DA) of the data obtained from both GC–MS and ICP-MS platforms. This study further highlights the usefulness of metabolite and elemental profiling complemented by suitable statistical tools to explore the prospect of an inherent correlation between grain quality features, biochemical composition and genetic background.