Objective Total flavonoid, antioxidant capacity, and differentially expressed proteins (DEPs) associated with flavonoids accumulation in the roots of different types of Ficus hirta were determined.

Method Roots of 3-year-old, 5-lobed (FF), 7-lobed (SF), and 9-lobed (NF) F. hirta Vahl. were collected for the determinations of flavonoid content and antioxidant activity as well as flavonoid synthesis-related DEP expressions by a proteomic analysis.

Result The total flavonoid content and antioxidant capacity of NF were significantly higher than those of the other two types. As indicated by the KEGG analysis, the DEPs were significantly enriched in phenylpropanoid and flavonoid synthesis pathways. Thirty-two key enzymes closely related to flavonoid synthesis were identified. They included the ones mostly upregulated in NF, such as phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), chalcone synthase (CHS), chalcone isomerase (CHI), and caffeic acid O-methyltransferase (COMT). Extensive synergistic interactions existed among these enzymes to jointly regulate the flavonoid synthesis in the plants.

Conclusion The DEPs associated with flavonoid synthesis in the different F. hirta Vahl. were identified at molecular level. The synergistic effect of the up-regulated key enzymes in the phenylpropanoid and flavonoid branch pathways appeared to result in the high flavonoid accumulation of NF variety.