AaF3'5'H involved in flavonoid synthesis in hairy roots of Actinidia arguta (Siebold & Zucc.) Planch. ex Miq.

Abstract

The kiwifruit (Actinidia arguta) is rich in diverse bioactive compounds, particularly flavonoids, which exhibit potent antioxidant, anti-inflammatory, and anti-tumor properties. Flavonoid 3'5'-hydroxylase (F3'5'H) is a key enzyme in the synthesis pathway of flavonoids. However, the functional role of the AaF3'5'H gene in A. arguta remains poorly understood. In this study, the AaF3'5'H gene was cloned. Its coding sequence (CDS) is 1344 bp in length, encoding a 447-amino-acid protein localized to the cytoplasm. Overexpression of AaF3'5'H significantly increased the flavonoid content in transgenic Arabidopsis and promoted growth and development. VIGS-mediated silencing of AaF3'5'H in A. arguta significantly reduced flavonoid accumulation and suppressed plant growth. In contrast, overexpression of AaF3'5'H in transgenic hairy roots enhanced root morphogenesis and significantly elevated total flavonoid content. Targeted metabolomics analysis further revealed 50 differentially expressed metabolites, among which 24 are upregulated and 26 are downregulated. KEGG pathway enrichment and metabolic mapping revealed that these differentially expressed metabolites were predominantly involved in flavonoid biosynthesis, flavone and flavonol biosynthesis, and phenylpropanoid biosynthesis. In conclusion, this study confirms that the AaF3'5'H gene plays a crucial role in positively regulating the biosynthesis of flavonoids and promoting the formation of root morphology. This provides a theoretical basis for the variety improvement of A. arguta and the utilization of flavonoid resources.

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