## 3 Results
### Figures, Tables, and Schemes  
In terms of identifying the relevant genes enriched in the metabolic or signaling pathways involved in grape aroma formation, the results showed that 793, 743, and 719 DEGs were enriched in the comparison of J2 vs. A2, M2 vs. J2, and M2 vs. A2 (Figure 5, Table S8). The aromatic substances in the fruits were mainly synthesized through fatty acid metabolism, amino acid metabolism, terpene metabolism, and monosaccharide and glycoside metabolism. In this study, \"Glycine, serine and threonine metabolism\", \"Cysteine and methionine metabolism\", \"Glycine, serine and threonine metabolism\", \"Tyrosine metabolism\", \"Phenylalanine metabolism\", and \"Phenylalanine, tyrosine, and tryptophan biosynthesis\" were selected according to the KEGG enrichment analysis of J2 vs. A2, M2 vs. J2, and M2 vs. A2. A total of 34, 18, and 12 DEGs were selected from the J2 vs. A2, M2 vs. J2, and M2 vs. A2 groups (Table S9). Five DEGs, i.e., _VvOMR1_ (VIT_08s0007g04310), _VvGLYX_ (VIT_09s0002g05200), _VvLPD2_ (VIT_14s0060g01330), _VvAK2_ (VIT_14s0068g01190),  
Figure 4: The number of DEGs (differentially expressed genes) in different groups. J: “Kyoho”; M: “Mei Xiangbao”; A: “Adenauer Rose”; 1: grape berries in the turning stage; 2: grape berries in the maturation stage.  
and _VvSHM7_ (VIT_18s0001g -04340), were discovered in both J2 vs. A2 and M2 vs. J2 comparisons, while two DEGs, _VvASP3_(VIT_04s0008g03770) and _VvASP1_(VIT_08s0058g01000), were discovered in both J2 vs. A2 and M2 vs. A2 comparisons (Table S9). _VvOMR1_ was significantly down-regulated in the \"Kyoho\" and \"AR\" and up-regulated in \"MXB\" from the turning stage to the maturation stage; _VvGLYK_ was significantly down-regulated in \"AR\" and \"MXB\"; _VvLPD2_ was significantly down-regulated in \"Kyoho\" and up-regulated in \"AR\" and \"MXB\"; _VvAK2_ was significantly down-regulated in all three cultivars; _VvSHM7_ and _VvASP3_ were both up-regulated in \"Kyoho\" and \"AR\"; and _VvASP1_ was significantly up-regulated in all three cultivars (Figure 6). Moreover, four common differentially expressed transcription factors, namely, _VvERF05_(VIT_12s0059g00280), _VvERF4_(VIT_19s0014g02240), _VvMYB46_(VIT_16s0039g01920), and _VvMYB340_ (VIT_14s0066g01090), were discovered. qRT-PCR verification showed that _Vv_ERF053 was significantly down-regulated in \"AR\" and up-regulated in \"MXB\" from the turning stage to the maturation stage; _Vv_ERF4 was significantly down-regulated in \"AR\" and up-regulated in \"Kyoho\" and \"MXB\"; VvMYB46 was significantly up-regulated in all three cultivars; and VvMYB340 was significantly down-regulated in all three cultivars (Figure 7a).  
Figure 5: KEGG enrichment analysis of differentially expressed genes for three cultivars at their maturation stage.(**a**) DEGs of the groups J2 vs. A2, (**b**) DEGs of the groups J2 vs. M2. (**c**) DEGsof the groups A2 vs. M2.  
Figure 6: Candidate genes and qRT-PCR verification. Green bars represent grape turning stage and red bars represent grape maturation stage. Error bars represent the SD of three biological replicates.  
To discover the transcription factors significantly related to structural genes and key metabolites, we calculated the Pearson correlation coefficients (_p_ < 0.05) for 11 candidate genes and 14 key metabolites (Figure 7b). The result showed that _VvGLYK_ was negative with most of these metabolites; _VvAK2_ was positive with XMW0132 and negative with KMW0212; _VvASP3_ was positive with KMW0148 and _VvLPD2_ and negative with NMW0071; _VvASP1_ was positive with _VvSHM7_ and negative with _VvOMR1_ and _VvAK2_; _VvERF053_ was significantly positive with _VvOMR1_ and _VvLPD2_; _VvERF4_ was significantly positive with _VvOMR1_ and negative with _VvASP3_; _VvMYB46_ was significantly positive with KMW0148, KMW0257, _VvOMR1_, and _VvAK2_; and _VvMYB340_ was significantly positive with _VvSHM7_ and _VvASP1_.