Comparative Proteomics Analysis Of The Difference In Fruit Size,Sugar And Acid Content Between Jujube And Wild Jujube

Ziziphus jujuba Mill.is an economically important fruit crop in China,with abundant nutritious.Fruit size,sugar and acid content are important traits of jujube fruit and affect the jujube quality and market value.Therefore the mechanism of fruit enlargement,sugar and acid metabolism are always been important to researchers.However,there are few reports on the proteome of jujube fruits.In this study,we observed the cells characteristic during the development of jujube and wild jujube?Z.jujuba var.spinosa?fruits,detected the phytohormones,and combined with transcriptome and proteome to explore the main factors and key genes causing jujube fruit expansion.At the same time,we compared the content of sugar and organic acids in jujube and wild jujube fruits,detected the enzyme activity realted to sugar/acid metabolism,and analyzed the dynamic changes of proteome during fruit development,revealing the metabolic mechanisms of sugar and organic acids in jujube fruit.The main results are as follows:?1?Within 7 weeks after flowering,the number of jujube pulp cells increased by 4 times and the cell volume increased by 9 times.At 7 weeks after flowering,the number of jujube pulp cells was 3 times that of wild jujube,and the volume of jujube pulp cell was 1.5 times that of wild jujube.The jujube fruit began to expand from the 5 weeks after flowering,and occupied 44.3%of the jujube pulp area at 7 weeks after flowering.At this time,the intercellular space of wild jujube cells accounted for 10.0%of the pulp area.?2?Toatlly,43,986 peptides and 5,400 proteins were identified in this study.It accounted for 19.7%of the jujube gene set.Compared with the proteins expression level of jujube and wild jujube,1012 differential proteins were identified.The protein upregulated in jujube fruits was mainly enriched in carbohydrate metabolism.The proteins expression level of jujube fruit at different developmental stages were analyzed.It was found that a total of 943 proteins were differentially expressed during the development of jujube fruits.The differential proteins between the enlarging and the white mature fruit were mainly enriched in the carbohydrate metabolism process.?3?The content of GA₃ and ZT increased first and then decreased in jujube fruits.The content of GA₃ in jujube fruit was always higher than that of wild jujube.The content of ZT in jujube fruits was significantly higher than that of wild jujube at 40 days after flowering.Comparative proteome analysis found that the expression levels of ZjGID1.4 and ZjYUCCA1in jujube fruits were significantly higher than that of jujube.The transcriptome results showed that the expression levels of ZjGA20ox1,ZjGA20ox6 and ZjGID1.1 in jujube fruit were significantly higher than that of wild jujube fruit.On the contrary,ZjDELLA11,ZjDELLA 17,ZjSPY13 highly expressed in wild jujube.In the cytokinin signal transduction pathway,ZjAHK2 and ZjB-ARR9,11 were highly expressed during jujube fruit development.In contrast,ZjA-ARR5 lowly expressed in jujube fruit.In the IAA signal transduction pathway,the expression levels of ZjARF4,16,23 and ZjSAUR7 in jujube fruits were significantly higher than that of wild jujube.?4?Sucrose was the principal form of jujube and wild jujube sugar,and the mainly accumulation period from enlarging to fully red stage.The sucrose content of jujube fruit was about 3 times that of wild jujube fruit in the fully red stage.Correlation analysis showed that AI and SSc activity were negatively correlated with sucrose content.On the other hand,SSs and SPS were positively correlated with sucrose content.SSs and SPS activities were significantly higher in jujube fruit than in wild jujube.Proteome analysis showed that the expression levels of ZjSPS1,ZjSPS2 and ZjSS2 were positively correlated with the sucrose content.The expression levels of ZjSPS1,ZjSS2 and ZjSUT4 in jujube fruits were higher than that of wild jujube.?5?The content of malic acid and citric acid during the development of wild jujube fruit were always significantly higher than that of jujube.In this study,NAD-MDH was positively correlated with malic acid content.CS was negatively correlated with citric acid content.The activity of CS and NAD-MDH in wild jujube was higher than that of jujube.The Cyt-ACO activity of wild jujube fruit was lower than that of jujube.Proteome analysis showed that the expression levels of ZjMDH3 and ZjMS were positively correlated with the content of malic acid,and the expression levels of ZjMDH3 and ZjMS in wild jujube fruit were higher than those in jujube fruit.Conversely,ZjNADP-ME3 was highly expressed in jujube fruits.The expression level of ZjACO1 and ZjACO2 were negatively correlated with the content of citric acid,and their expression level in wild jujube were lower than that in jujube.However,ZjATP-CS1 was highly expressed in wild jujube.