Comparative metabolomics identifies enhanced ursane-type triterpenoids and antioxidant capacity in Actinidia arguta...

Chemical diversity is crucial for plant ecological adaptation and nutritional value. In kiwifruit, secondary metabolites such as terpenoids influence key traits such as flavor and nutraceutical properties, however, their diversity across different species and cultivars remains poorly characterized. This study employed UPLC-MS/MS-based metabolomics to profile terpenoids in five varieties representing both Actinidia chinensis (cultivars 'Guichang', GC; 'SunGold', SG; and a wild type, WL) and Actinidia arguta (cultivars 'Maolvfeng', LC; 'Danyang', DY). We identified 309 terpenoids, revealing profound diversity. Notably, the commercial A. chinensis 'SunGold' (SG) and A. arguta 'Danyang' (DY) exhibited the highest total terpenoid content, while SG uniquely possessed a soluble sugar content 2.4 to 6 times greater than other varieties. Both varieties also showed the strongest antioxidant capacity (455.20 and 438.91 µg TE/g FW, respectively), suggesting their superior nutraceutical potential. Multivariate analysis confirmed distinct terpenoid fingerprints, with DY enriched in ursane-type triterpenes e.g., pomolic acid, 1-oxo-siaresinolic acid, camellisin B, and siegesbeckic acid, while SG was uniquely abundant in seco-iridoids like geniposide (442-fold higher than WL). Within A. chinensis, the cultivated 'Guichang' (GC) showed a significant suppression of most triterpenoids compared to its wild relative (WL), demonstrating a possible breeding or selection effect. Our findings demonstrate that terpenoid profiles are likely influenced by genetic background, both at the species and cultivar level, providing a metabolic roadmap for the targeted breeding of kiwifruit with optimized health, nutraceutical, and sensory properties.