Fig. 3

Analysis of the metabolites detected by the metabolome. Volcano plots displaying the up-regulated, down-regulated and no-regulated metabolites between two development stages of walnut endopleuras (A, B, and C). Green dots in the graph represent down-regulated differentially expressed metabolites, red dots represent up-regulated differentially expressed metabolites, and gray represents metabolites that were detected but not significantly different. D K-means analysis of differential metabolites. The horizontal coordinate indicates the name of the sample, the vertical coordinate indicates the standardized metabolite relative content, and the sub class represents the metabolite class number with the same change trend. E heatmap of differential flavonoid metabolites. F heatmap of differential Phenolic acid