Fig. 4

OPLS-DA score (a) and coefficient or loading (b) plots derived from ¹H NMR spectra of soybean adventitious roots for metabolic differentiation between soybean adventitious roots cultured under a dark condition (Dark) or under a fluorescent light irradiation condition (Light). OPLS-DA models were derived from ¹H NMR spectra of soybean adventitious root extracts, showing identifications of metabolites responsible for metabolic differences. The upper section in panel B represents higher levels of metabolites in soybean adventitious roots cultured under a light condition than in soybean adventitious roots cultured under a dark condition, whereas the lower section represents lower levels of metabolites in soybean adventitious roots cultured under a light condition. The color code in the loading plot corresponds to the correlation among variables. All OPLS-DA models were generated with one predictive component and one orthogonal component. Their reliabilities and predictabilities were indicated by R²X and Q², respectively. These models were validated by permutation tests (Additional file 1: Fig. S1). Abbreviations of assigned metabolites are the same as shown in legends of Fig. 2