Fig. 4

Accumulation patterns of specific metabolites (amino acids, sugar alcohols and lipids) in R vs. P (a); DAM (lipid, sugar alcohol, flavonoid) accumulation patterns in R vs. W and R vs. Y (b). W represents white kernels, Y represents yellow kernels, R represents red–purple kernels, and P represents purple–black kernels. Metabolites marked with red and green indicate up- and down-accumulated in maize kernel, respectively