Large-Scale Volatile Profiling of 292 Tea Germplasms Reveals Terpenoid Diversity and Regional Aroma Biomarkers

Volatile organic compounds (VOCs) are key determinants of tea quality, yet their large-scale variation among diverse germplasms has not been systematically characterized. In this study, 292 representative tea germplasms were analyzed using HS-SPME-GC-MS. Regional comparisons and receiver operating characteristic analysis highlighted heptanal and neophytadiene as robust biomarkers for distinguishing China’s four major tea-growing regions. Leaf-type comparisons showed that medium- and small-leaf germplasms had higher total terpenoid levels, whereas large-leaf germplasms were enriched in limonene, linalool, E-β-ionone, and camphene. Random forest modeling further identified camphene, citral, and allo-ocimene as candidate biomarkers for differentiating leaf types. Geographical variation analysis revealed that Chongqing germplasms exhibited the highest total terpenoid content but the lowest Shannon diversity index (H′), while Guangdong germplasms had the lowest terpenoid content but the highest H′. These findings not only uncover the extensive diversity of VOCs in tea germplasm collections but also provide valuable molecular resources for germplasm differentiation and aroma-oriented breeding strategies.