KEGG enrichment of metabolites
KEGG analysis identified four significant pathways related with amino acids (alanine, cyano amino acid, phenylalanine, alanine aspartate and glutamate) in wheat. Similar with wheat, metabolisms associated with amino acids (Alanine, phenylalanine, cysteine, methionine and pyrimidine) and nucleotides (purine and pyrimidine) were significantly enriched in rice. These results suggest that O3 affects the synthesis of certain amino acids in wheat and rice. In soybean, in addition to amino acid metabolism, the biosynthesis of alkaloids and terpenoids were also altered by O3 (Fig. 5).