## 3 Experimental Section
### Quantification of Linalool and Its Derivatives by GC-MS  
The berry samples without seeds, stored at \(-80\)\({}^{\circ}\)C, were crushed and steeped for 140 min at 4 \({}^{\circ}\)C, and then were immediately centrifuged at 4 \({}^{\circ}\)C and \(6000\times g\) for 10 min. The supernatant was collected. The glycosidically-bound linalool and its related compounds were isolated by the Solid-Phase Extraction (in sort, SPE) method. In short, 5 mL of the clear juice was passed through the Cleanert PEP-SPE column (Bonna-agela Technologies,Tianjin, China, 200 mg/6 mL), which was activated in advance with 10 mL methanol (Sinopharm Chemical Reagent Beijing Co., Ltd., Beijing, China) and 10 mL water. And then the water-soluble compounds were eluted with 5 mL of water, the free volatiles with 10 mL of dichloromethane (Sinopharm Chemical Reagent Beijing Co., Ltd., Beijing, China) and the target bound volatiles with 20 mL of methanol, sequentially. The flow rate was about 2 mL/min. The methanol elute was evaporated to dryness by reduced pressure distillation at 30 \({}^{\circ}\)C and then redissolved in 5 mL citrate-phosphate buffer solution (2 M, pH 5.0). Subsequently, 100 \(\upmu\)L of the AR 2000 solution (DSM Food Specialties, Seclin, France, 100 mg/mL) was added to the glycoside extract and the mixture was vortexed and enzymatically hydrolyzed in an incubatorat 40 \({}^{\circ}\)C for 16 h to liberate the free aroma according to optimum conditions described previously [49]. The tube containing the mixture was stored at 4 \({}^{\circ}\)C and the liberated volatiles were extracted through SPME fiber within two days. Free types of linalool and its related compounds were extracted using HS-SPME according to the method of [PERSON] _et al._ (2009) with minor modification [49]. That is, the grape juice of 5 mL, 10 \(\upmu\)L 4-methyl-2-pentanol (1.039 mg/mL water, internal standard, Sigma-Aldrich) and 1.00 g NaCl (Sinopharm Chemical Reagent Beijing Co., Ltd., Beijing, China) were blended in a 15-mL sample vial tightly capped with a PTFE-silicon septum and containing a magnetic stirrer. The procedures of HS-SPME and GC-MS analysis were performed as described in the above section \"assay of terpene synthase activity\". As to each sampling point, three independent extraction replicates were conducted. The quantification procedure used was based on our prior research with some modifications [50]. According to the average concentration of sugar and acids in grape juice, the model solution consisted of 180 g/L glucose and 7 g/L tartaric acid and pH value was adjusted to 3.3 with NaOH (Sinopharm Chemical Reagent Beijing Co., Ltd., Beijing, China). The chemical standards used for quantification were linalool (96.5%, Sigma-Aldrich, Switzerland) and furan linalool oxides (97% purity, mixture of _cis_- and _trans_-furan linalool oxide, Fluka, Japan). Each standard was dissolved with ethanol (HPLC quantity, Anpel Co., Ltd., Shanghai, China). All the standard stock solutions were then combined together, and eight different and successive concentrations of mixed standard solutions were prepared in juice model solution. Standard solutions of each level was extracted by HS-SPME and analyzed by GC-MS under the same condition as that of grape samples. The calibration curve of linalool was obtained and directly used for linalool quantification. As for furan linalool oxide, the calibration curve was acquired using the sum of two peak areas corresponding to _cis_- and _trans_-isomers, respectively. To quantify either of furan isomers in grape berry, we used this calibration curve to estimate the content of _trans_- or _cis_-furan linalool oxide on the basis of the peak area of single isomer. Also two pyran linalool oxide isomers were quantified using this furan calibration curve because there were no pyran linalool oxide standards bought. Similarly, only the peak area of the corresponding compound was considered when the content of _trans_- or _cis_-pyran linalool oxide was estimated.