3.3 KEGG functional annotation classification and enrichment analysis of DEPs
The DEPs were also investigated using the KEGG database. Figure 3A revealed that the DEPs were annotated on five primary metabolic pathways, including metabolism, genetic information processing, environmental information processing, cellular process and organismal systems (Table S5). A large number of proteins were annotated to pathways such as carbohydrate metabolism, amino acid metabolism, metabolism of cofactors and vitamins. As can be seen in Figure 3B, in terms of primary metabolism, proteins were enriched in various amino acids metabolism including glycine, serine and threonine metabolism and so on, as well as glycolysis/gluconeogenesis, indicating that the physiological activity of TH from FXS was vigorous. For the secondary metabolism, a total of 9 DEPs (6 down-regulated and 3 up-regulated) were associated with flavonoids biosynthesis with no significant protein enrichment in pathway. Overall, the quality disparities in TH from different hosts were primarily caused by DEPs implicated in biosynthetic pathways of bioactive constituents (Table S6).