Metabolite profiling of the short-term responses of rice leaves (Oryza sativa cv. Ilmi) cultivated under different LED lights and its correlations with antioxidant activities

Abstract

Metabolite profiling of rice leaves (Oryza sativa cv. Ilmi) was performed to investigate the short-term responses to different light-emitting diode (LED) lights, blue (B), green (G), red (R), white (W), shade (S), by using gas chromatography-ion trap-mass spectrometry (GC-IT-MS) and ultra-performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-Q-TOF-MS) with multivariate analysis. Clear grouping patterns of each light-grown sample, except G and W, were shown in partial least squares-discriminant analysis (PLS-DA). Thirty-two primary metabolites and eleven secondary metabolites were selected and visualized using heatmap. Antioxidant activities of rice leaves followed the order B=W=G>R>S and isoorientin-2''-O-glucoside, isovitexin-2''-O-glucoside, isoorientin-2''-O-(6'''-ρ-coumaroyl)-glucoside, and isoscoparin-2''-O-glucoside showed similar relative differences and had higher Pearson's correlation coefficients than other metabolites in correlation network. According to the orthogonal projection to latent structures-discriminant analysis (OPLS-DA) between B and R, the levels of amino acids, organic acids, fatty acids, and flavonoid glycosides were relatively high in B, whereas the glucose and fructose levels were high in R.

Keywords: Antioxidant activity; GC–IT-MS; LED lights; Metabolite profiling; Oryza sativa; UPLC–Q-TOF-MS.