Genome-wide discovery and characterization of terpene synthases contributing to strawberry aroma metabolism

Strawberry (Fragaria × ananassa) is a globally cultivated fruit crop appreciated by consumers for its unique flavor and aroma. Major groups of volatile organic compounds that define strawberry aroma include terpenes, fatty acid esters, furanones, and benzenoids, with complex terpene blends contributing characteristic fruity, citrus, and floral notes. Here, we report the genome-wide identification and functional analysis of the terpene synthase (TPS) family that governs terpene chemical diversity in strawberry. Mining of the allo-octoploid genome of the commercial "Royal Royce" cultivar identified 75 TPS gene candidates. Biochemical characterization of 33 mono-, sesqui- and di-TPS enzymes via recombinant protein assays and/or microbial co-expression studies demonstrated TPS activities involved in the biosynthesis of nearly two-thirds of known strawberry terpenes as well as products not previously described in octoploid strawberry. Complementary metabolomic and transcriptomic studies across a diversity panel of strawberry accessions illustrated substantial variation in the composition and abundance of more than 30 common and accession-specific terpene aroma metabolites. Analysis of 2 commercial accessions, "Royal Royce" and "Mara de Bois," with contrasting aroma profiles further revealed accession-specific alterations of terpene metabolism during fruit ripening. These findings expand our understanding of the biosynthetic genes and pathways underlying strawberry terpene metabolism and provide resources to develop breeding strategies toward improving desirable strawberry aroma traits.