Abstract: Abstract: [Objective] This study aims to elucidate the effect of varietal differences in selenium (Se) enrichment levels on volatile metabolite profiles and to explore the potential metabolic pathways through which Se regulates the synthesis of tea aroma compounds. [Methods] Five oolong tea cultivars (Rougui, Shuixian, Queshe, Jinguanyin, and Huangguanyin) were used as experimental materials. The selenium content in the tea leaves was determined using inductively coupled plasma mass spectrometry (ICP-MS). Non-targeted metabolomics analysis of volatile compounds was conducted using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS), followed by qualitative and quantitative analysis of volatile components employing multivariate statistical methods. [Results] Under identical ecological and cultivation conditions, significant differences in selenium content were observed among the five oolong tea cultivars, ranking from highest to lowest as follows: Queshe > Shuixian > Jinguanyin > Rougui > Huangguanyin. A total of 615 volatile compounds were identified, with hydrocarbons, terpenoids, alcohols, esters, and aldehydes being the predominant classes, collectively accounting for 80% of the total volatile components. Through pairwise comparisons using criteria of Variable Importance in the Projection (VIP) > 1 and p < 0.05, 82 major differential aroma compounds were screened. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that these differential compounds significantly affected terpenoid and polyketide metabolism. Furthermore, combined with odor activity value (OAV) analysis, 17 key aroma compounds with OAV > 1 were identified, including linalool and its oxides, geraniol, α-ionone, and β-ionone. Correlation and absolute quantitative analysis confirmed that tea selenium content was significantly positively correlated with C13-norisoprenoids (β-ionone)（r = 0.97, p < 0.001） and (E)-2-nonenal（r = 0.89, p < 0.05）. [Conclusion] Varietal differences in selenium enrichment levels, determined by genetic characteristics, may influence the aroma quality of oolong tea by regulating the synthesis of C13-norisoprenoid aroma compounds derived from carotenoid metabolism. This study provides a theoretical basis for breeding tea cultivars with high selenium accumulation and for the simultaneous enhancement of selenium nutrition and quality in tea.

Key words: Oolong tea, Selenium enrichment level, Varietal differences, Aroma components, Carotenoids, Metabolic pathways