Study On The Dynamic Changes Of N-glycan During Peach Fruit Ripening And Softening

Prunus(Prunus persica)belongs to the subgenus Prunus of Rosaceae,which is abundant in southern China and has many years of cultivation history.The peach fruit is tender,less slag and juicy,and has a unique flavor.However,due to its thin skin,it is easy to be mechanically damaged and cause secondary damage.It is not resistant to storage and transportation and has a short shelf life.It is developed based on the existing fruit softening mechanism after harvest.Fresh-keeping technology cannot effectively extend the shelf life of peaches,so it is necessary to explore new softening control mechanisms.During fruit ripening,N-glycan change regularly during fruit ripening.Exoglycosidase is a key enzyme in the processing of N-glycan in plant cells,and plays an important role in controlling fruit softening and extending shelf life.Based on this,studying the dynamic changes of N-glycan in the process of peach fruit maturation and softening has obvious innovation and great significance for the cultivation of new storable varieties or the improvement of peach fruit storage and preservation technology.In this thesis,peach fruits with different fleshy types(soft solute type "Hujing",hard solute type "Xiahui No.6",Stonyhard type "Xiacui")are the research objects,and the peach fruit protein N-glycome is released by enzymatic hydrolysis.UPLC was used for separation and detection,and its structure was analyzed by MALDI-TOF-MS/MS.The peak area of N-glycan was integrated to analyze the relative content of N-glycan,and the physiology of peach fruit during ripening and softening was detected.Index changes,using p NP-derived monosaccharides as substrates to determine the changes in N-glycan exoglycosidase activity,using q RT-PCR technology to detect the expression of peach fruit ripening and softening related genes,and exploring N-glycans to talk about national maturity Softening regulation mechanism.The main research contents and results are as follows:1.Changes in N-glycan content during peach fruit ripening and softeningUsing PNGase F and PNGase Rc as tool enzymes,the N-glycans of peach fruits during the ripening and softening process were subjected to enzymatic interpretation,and then the structure of N-glycan was identified,and the relative content of N-glycan was analyzed.The results showed that there were 15 structures in the N-glycan group of peach fruit,including 6 high-mannose types,8 complex types and 1 hibrid type.During the ripening process of peach fruits,the N-glycan structure of different varieties of peach fruits is the same.During storage,the structure type is unchanged,and the relative content changes.M3,MMXF and Gn Gn MXF have significant changes,and the relative content of M3 and MMXF increases,the relative content of Gn Gn MXF decreases.It is speculated that the characteristic N-glycans that affect the ripening and softening of the three fleshy peach fruits are high mannose type M3,complex N-glycans MMXF and Gn Gn MXF.2.Analysis of N-glycan metabolism exoglycosidase activity and related gene expressionThe results prove that the relative content of the N-glycan structure changes during peach fruit ripening in Chapter 2.The p NP-derived monosaccharide is used as the substrate to determine the change of N-glycan exoglycosidase activity,and the related enzymes gene expression level are determined by q RT-PCR.The results showed that the vitality of α-Man,β-Hex and β-Gal increased during the ripening process of the three fleshy peach fruits.In terms of increasing amplitude,β-Gal>β-Hex>α-Man.During the ripening process of different fleshy peach fruits,the expression patterns of the three exoglycosidase genes are different,and the gene expression patterns of the same gene are also different in different peach fruits.The gene expression of Man4853 and Hex0020 of soft solute type "Hujing" was positively correlated with ethylene release,and the gene expression of Hex0754 in the three fleshy peach fruits was positively correlated with firmness.