## 4 Conclusions  
In this work, we showed that cluster thinning affects the contents of free and bound monoterenes during the ripening of Muscat Hamburg grape. We observed that more intense thinning produced higher concentrations of total monoterenes, particularly in their bound forms. The total concentration of glycosylated bound monoterenes was lowest in the 0.7 cluster per shoot remaining treatment at the early stage of grape development and highest in this treatment at the later stages. Cluster thinning also regulated the expression levels of several key enzymatic genes in the monoterenes biosynthesis pathway, the expression levels of three _VviDXS_ genes were upregulated in the 0.7 cluster per shoot remaining-treated grapes, which correlated well with the total monoterenes profiles at harvest. Our data provide a theoretical basis for the molecular consequences of cluster thinning, particularly monoterene accumulation. These results are of a preliminary nature on the basis of one vintage year, therefore, further research with more harvest years is required to determine how cluster thinning affects the monoterenes profiles of grapes. Figure 9: Heat map of DEGs involved in the monoterenes synthesis pathway (**a**) and correlation of FPKM analyzed by RNA-Seq (x axis) and the data obtained using qRT-PCR (y axis) (**b**). Heat maps depict the normalized gene expression values, which represent the means \(\pm\) SD of three biological replicates. Expression values are presented as FPKM normalized counts. G3P, glyceraldehyde 3-phosphate; DXS, 1-deoxy-D-xylulose-5-phosphate synthase; DXR, 1-deoxy-D-xylulose 5-phosphate reductoisomerase; MEP, 2-C-methyl-D-erythitol 4-phosphate; HMBPP, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate; HDR, 1-hydroxy-2-methyl-2-(E)-butenyl-4- diphosphate reductase; IPP, isopentenyl pyrophosphate; DMAPP, dimethylallyl pyrophosphate; IPPI, IPP-isomerase; GGPPS, geranyl pyrophosphate synthase; GPP, geranyl pyrophosphate; AACT, acetoacetyl-CoA thiolase; HMGS, 3-hydroxy-3-methylglutaryl synthase; HMG-CoA, 3-hydroxy-3-methylglutaryl-CoA; HMGR, 3-hydroxy-3-methylglutaryl-CoA reductase; MVA, mevalonate; MK, MVA kinase; MVP, mevalonate-5-phosphate; PMK, phospho-MVA kinase; MVPP, mevalonate-5-diphosphate; MPDC, diphospho-MVA decarboxylase; MVPP, mevalonate-5-pyrophosphate. Three genes were selected for the quantitative RT-qPCR experiments, including DXS, HMGR, and GPPS. **Supplementary Materials:** The following are available online at [[https://www.mdpi.com/article/10.3390/foods10112718/s1](https://www.mdpi.com/article/10.3390/foods10112718/s1)]([https://www.mdpi.com/article/10.3390/foods10112718/s1](https://www.mdpi.com/article/10.3390/foods10112718/s1)), Figure S1: Technological parameters of grape berries from different loading grapes during the ripening stages, Figure S2: Changes of total monoterpenes (total free and total bound) profiles in Muscat Hamburg grape at six developmental stages, Figure S3: eggNOG function classification on brown module genes, Figure S4: KEGG analysis on brown module genes. Table S1: Changes of free monoterpenes profiles in Muscat Hamburg grape at six developmental stages, Table S2: Changes of bound monoterpenes profiles in Muscat Hamburg grape at six developmental stages. Table S3: Sequencing Data Statistics, Table S4: KEGG enrichment analyses of DEGs, Table S5: Number of genes in each WGCNA module. **Author Contributions:** Conceptualized, designed the research, and provided materials, Y.J. and X.Y. ; Methodology and conducted the experiments; Y.J. and X.Y. ; Analyzed the data and wrote the manuscript, Y.J. and X.Y. ; Review and editing, Y.F. and Z.Z. ; Funding acquisition, Z.Z. All authors have read and agreed to the published version of the manuscript. **Funding:** \"This research was funded by the National Key Research and Development Project, grant number 2019 YED1002500\" and \"The APC was funded by National Key Research and Development Project\". **Institutional Review Board Statement:** This study did not involve humans or animals.