Acylphloroglucinol Biosynthesis in Strawberry Fruit

Area of Science:

• Plant Biochemistry
• Metabolomics
• Fruit Ripening

Background:

• Phenolic compounds, including acylphloroglucinol (APG)-glucosides, are vital for fruit health benefits.
• Understanding the biosynthesis of these metabolites in crops like strawberry (Fragaria × ananassa) is crucial for agricultural and pharmaceutical applications.

Purpose of the Study:

• To investigate the biosynthesis of acylphloroglucinol (APG) aglycones in strawberry fruit.
• To explore the function of chalcone synthase (CHS) enzymes in the production of APGs and anthocyanins during fruit ripening.

Main Methods:

• Reverse genetic analysis of ripening-related genes in transgenic strawberries.
• Enzymatic characterization of recombinant Fragaria vesca chalcone synthase (FvCHS) proteins.
• Metabolite analysis using feeding studies with isotopically labeled amino acids and analysis of CHS-silenced fruit.

Main Results:

• Identified four acylphloroglucinol (APG)-glucosides as native strawberry fruit metabolites.
• Demonstrated that FvCHS enzymes possess dual functionality, catalyzing the formation of APG aglycones (phlorisovalerophenone and phlorisobutyrophenone) and naringenin chalcone.
• Showed that suppression of CHS activity significantly decreased APG glucosides and anthocyanins while increasing branched-chain amino acid-derived volatiles.

Conclusions:

• Strawberry plants synthesize pharmaceutically important APGs via dual-functional CHS/(phloriso)valerophenone synthases during fruit ripening.
• Gene duplication and adaptive evolution of CHS likely contributed to this dual function, a mechanism potentially applicable to other plant species.
• Highlights the importance of experimental validation to uncover promiscuous gene functions missed by in silico analysis.