## 3 Results and Discussion
### PLSR-Based Characteristic Aroma Analysis  
The sensory evaluation results of the tasting panel were quantified by the MF (%) values (Table S3). From the overall level of MF (%) values, we found there were significant differences in black berry, floral, and green sensory characteristics, while there was no obvious divergence in spice and red berry sensory characteristics of the wine samples among various varieties and clones (Figure 3 and Table S3). The Merlot, Cabernet Franc VCR10, and Pinot Noir (except Pinot Noir 792) varieties had significantly lower sensory characteristics of black berries than the other wine samples, and the overall aroma reflected relatively weak characteristics of rip fruit. Merlot VCR1, Pinot Noir 375, Cabernet Franc 215, Cabernet Sauvignon 170, and two clones of Malbec had significant floral characteristics, and the floral characteristics of the wine samples from different clones were different. The green flavor is closely dependent on the maturity of varieties and we found that there was a large difference in green flavor among different clones of the same variety. However, there was no green in Malbec VCR6, which can be used to create a mature wine style. Noteworthily, the diversity of the characteristics of black berry and floral suggested that the adaptability between the terroir and varieties/clones in Hexi Corridor made an important contribution to the formation of these two flavors. That is to say, those two characteristics can provide a good reference for the shaping of wine style and the selection of related varieties in this region. We further performed the PLSR analysis of the volatile components and the corresponding sensory attributes of the wine samples to identify the key compounds contributing to the formation of those sensory characteristics. PLSR analysis was performed on the sensory characteristic attributes and the corresponding compounds in the wine samples. The regression results for the floral aromas with Merlot, Cabernet Sauvignon, Pinot Noir, and Malbec were satisfactory. The PLSR models of single sensory attributes of grape varieties with volatile aroma substances showed that floral aromas were positively correlated with ethyl caproate, ethyl 9-decenoate, hexanol, and (Z)-3-hexen-1-ol (Figure 4). As shown in Table S4, the correlation coefficients of ethyl caproate with the Merlot, Cabernet Sauvignon, and Pinot Noir samples were 0.061, 0.069, and 0.089, respectively; the correlation coefficients of ethyl 9-decenoate with the Merlot, Cabernet Sauvignon, and Malbec samples were 0.06, 0.038, and 0.056, respectively; the correlation coefficients of hexanol with the Merlot, Cabernet Sauvignon, and Malbec samples were 0.062, 0.116, and 0.056, respectively; and the correlation coefficients of (Z)-3-hexen-1-ol with the Merlot, Cabernet Sauvignon, and Malbec samples were 0.067, 0.121, and 0.057, respectively. Ethyl caproate, which is formed as a byproduct during the synthesis of long-chain fatty acids by yeast, presents aromas of apple, raw green banana, and pineapple, as well as floral aromas reported in Moscatel vine-shoots [26]. Ethyl caproate has been found to be a prominent volatile component of Cabernet Sauvignon, Cabernet Gernischt, Cabernet Franc and Chardonnay wines from parts of Hexi Corridor region. Ethyl caproate is an important volatile component of Marselan wines and is considered to be one of the compounds that distinguish wine regions [27; 28]. It is also an aroma commonly found in top-fermented beers [29]. In addition, ethyl caproate, an aroma component specific to Chinese strong-flavor baijiu, is one of the core components that determine the quality of baijiu [30]; therefore, it is possible that ethyl caproate is one of the main aroma compounds found in fermented spirits. Ethyl 9-decenoate has a pleasant floral aroma [22]. It is less reported but detected at higher levels in white wines [31]. This compound aids distinction between icewines and late harvest wines from the same wineries, grape varieties, and vintages in Canada and the Czech Republic [32].