Metabolomic Analysis on the Mechanism of Nanoselenium Biofortification Improving the Siraitia grosvenorii Nutritional and Health Value

Nanoselenium (nano-Se) foliar application is crucial for enhancing plant health. However, the mechanism by which nano-Se biofortification promotes the nutritional components of Siraitia grosvenorii remains unclear. In this study, nano-Se foliar application increased the carbohydrate and amino acid contents, including glucose (23.6%), fructose (39.7%), sucrose (60.6%), tryptophan (104.5%), glycine (85.9%), tyrosine (78.4%), phenylalanine (60.1%), glutamic acid (63.4%), and proline (52.5%). Nano-Se application enhanced apigenin (3.8 times), syringic acid (0.7 times), and 4-hydroxy-3,5-dimethoxycinnamic acid (1.4 times) of the phenylpropane biosynthesis pathways. Importantly, the SgCDS (31.1%), CYP-P450 (39.1%), and UGT (24.6%) were induced by nano-Se, which enhanced the mogroside V content (16.2%). Compared to the control, nano-Se treatment dramatically enhanced aromatic substances, including 2-butanone (51.9%), methylpropanal (146.3%), n-nonanal dimer (141.7%), pentanal (52.5%), and 2-pentanone (46.0%). In summary, nano-Se improves S. grosvenorii quality by increasing nutrients and volatile organic compounds and adjusting the phenylpropane pathway.