| 'Munage' grape(Vitis vinifera L.cv Munage)is one of the characteristic table berries of Xinjiang in China.Sugars and organic acids are the main flavor ingredients in fruits.Sulfur dioxide(SO2)is still widely used as preservative in grapes for commercial applications around the world.SO2 can effectively inhibit infection by pathogenic fungi and prolong fruit shelf life.The research on SO2 regulation of fruit quality basically stays at the physiological level and enzyme level,and the molecular mechanism is not clear.There are few studies about SO2 on the mechanisms of sugar and organic acid metabolism.In this study,'Munage'grape was used as the test material.The sulfur dioxide cling paper was used to treat grapes.To analyze the effects of SO2 on sugars and organic acids content of grapes during storage.Combined with RNA-Seq data to study the regulation effects of SO2 on sugar metabolism and malate metabolism related genes in grapes,analyze and plot the transcriptome mapping of sugar and malate metabolism,and study the role of SO2 on sugar metabolism and malate metabolism in 'Munage' grape during postharvest storage.The main findings are as follows:(1)The effect of SO2 on postharvest transcriptome data of grape fruits was analyzed.GO and KEGG analysis of differentially expressed genes(DEGs)revealed that SO2 caused large-scale reprogramming of the transcriptome in grape.SO2 significantly enhanced postharvest photosynthesis and promoted the activity of enzyme inhibitor of fruits,and significantly regulated the phenylalanine metabolism,tyrosine metabolism,isoquinoline alkaloid biosynthesis,plant hormone signal transduction,and carotenoid biosynthetic pathways.During the whole storage period,DEGs in SO2-treatment group and control group(CK)were significantly enriched in the pathway related to sugar metabolism.(2)The effects of SO2 on postharvest sugar content and sugar metabolism were studied.High performance liquid chromatography(HPLC)determined the change of sucrose,glucose,fructose content in grape.SO2 can maintain the content of sugars in grape fruits,glucose content increased significantly at 0-10 d.On the 60 d,the content of sucrose,glucose and fructose in SO2-treatment were 0.46 mg/g?6.13 mg/g?6.40 mg/g higher than CK.It was verified by qPCR that the relative expression of sugar metabolism-related genes has a consistent trend with the expression of the corresponding genes in the transcriptome map.SO2 possibly maintained high level of sucrose,glucose and fructose by regulating the expression of VvCWINV,VvCIN,VvSuSy and VvSPS1 and regulated postharvest photosynthetic activity of grapes by regulating the expression of VvHxK2,VvFBA,VvGAPDH and VvPGK.(3)The effects of SO2 on postharvest organic acids content and malate metabolism were investigated.HPLC determined the change of acids in grape.The results showed that SO2 could maintain the content of tartaric acid,L-ascorbic acid and citric acid and promote the decomposition of L-malic acid in grape.On the 60 d,the content of tartaric acid,L-ascorbic acid and citric acid in SO2-treatment were 0.13 mg/g?0.34 mg/100g?0.02 mg/g higher than CK,the content of L-malic acid were 0.64 mg/g lower than CK.It was verified by qPCR that the relative expression of malate metabolism-related genes has a consistent trend with the expression of the corresponding genes in the transcriptome map.The content of L-malic acid was consistent with the change of VvMDH expression level.SO2 up-regulated the expression of VvmtMDH,VvLDH,VvNADP-ME,VvPDCl and down-regulated the expression of VvMDH,VvcytMDH,VvPDC2,VvADH to regulate malate metabolism and promote decomposition of L-malic acid of fruits.In summary,SO2 can regulate related genes of sugar and malate metabolism during storage of grapes,improved postharvest photosynthesis,maintained the content of sucrose,glucose,fructose,tartaricacid,Lascorbic acid and citric acid,and promoted decomposition of L-malic acid to delay the senescence and keep the quality of grapes during storage. |
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