Fig. 5

Effects of different ratios of nano-Se (0, 0.2, and1 mg/L) and Cd (0 and 1 mg/L) on the lignin biosynthesis-related metabolites and genes. A heatmap (A) was utilized to analyze the alteration of lignin-related metabolites. Levels of p-coumaric acid (B), sinapyl alcohol (C), phenylalanine (D), p-coumaroyl alcohol (E), caffeoyl alcohol (F), p-coumaraldehyde (G), cinnamic acid (H), coniferaldehyde (I), lignin (J); and the expression of C3H (K), CAD (L), 4CL (M), PAL (N), HCT (O), and COMT (P) were determined in the roots of pepper plants. Different letters across treatments indicate significant differences at P < 0.05