Transcriptome analysis of Shine Muscat grape treated with 1-MCP and SO₂ preservatives

【Objective】To analyze the gene differential expression of Shine Muscat grape during storage under two preservation treatments,so as to provide theoretical reference for studies on the regulation mechanism of preservative treatments on stored grape fruit quality from the perspective of molecular biology.【Method】Shine Muscat grapes were used as test material, treated with 1-MCP and SO₂ preservative agents respectively and then was put in cryogenic storage (-1-1℃). The fruits without any preservative agent were taken as the control. Transcriptome analysis was performed on the fruits treated with each preservative treatment and the control group after 1, 5, 9, 13 and 17 weeks of storage period,respectively. The liability of sequencing was confirmed by qRT-PCR experiment.【Result】 A total of 371.64 Gb of raw data was obtained from the transcriptomic sequencing of groups of two preservative treatments and the control. Clean data of each sample reached 6.03 Gb. GC content was 46.28%-47.53%, and Q30 percentage was more than 93.50%, and the matching rate to grape reference genome was 75.75%-90.23%. The number of DEGs between 1-MCP treatment and control reached the highest value at 13 weeks after storage, while the number of differentially expressed genes(DEGs)between SO₂ treatment and control, SO₂ treatment and 1-MCP treatment reached the highest value at 5 weeks after storage. At the 1^st and 13^th weeks of storage. The number of DEGs between 1-MCP treatment and control was 965 and 2881, respectively. The number of DEGs between SO₂ treatment and control reached the highest at 3698 and 1628, in the 5th and 9th weeks of storage,respectively. At 17^th weeks of storage,no significant difference appeared in the number of differential genes obtained by pairwise comparison between treatment groups and the control. The results also showed that the changes of cellular components, molecular functions and biological processes in fruits during 1-5 weeks of storage were much more dramatic than those in the middle and late stages of storage. Under the regulation of MYB, AP2/ERF-ERF, NAC, GARP-G2-like, HB-HD-ZIP and WRKY transcription factors, the expression of structural genes related to monoterpene biosynthesis decreased rapidly after 5 weeks of storage. The expression of genes related to phenylpropane-flavonoid, carotenoid and monoterpene metabolic pathways in all samples based on real-time quantitative PCR(qRT-PCR)were basically consistent with the transcriptome sequencing analysis results.【Conclusion】1-MCP and SO₂ preservative agents have different effects on stored Shine Muscat grape. The former inhibits fruit ripening and senescence more gently than the latter, and delays senescence by blocking ethylene binding to receptors and inhibiting the expression of ETR, EIN3 and ERF1/2, three key genes in ethylene signaling pathway. Transcription factors MYB, AP2/ERF-ERF, NAC, GARP-G2- like, HB-HD-ZIP and WRKY are strongly correlated with monoterpenoid synthesis genes. Correlations among the six transcription factors which may regulate monoterpenoid synthesis or other ripening and senescence processes through interaction are obvious.