Physiological Differences And Mechanism Of Fruit Softening During The Development Of Lycium Barbarum L Ripening

The rapid softening of Lycium barbarum L fruit in the late stage of development makes it extremely difficult to store and transport the fruit,reduces the nutrition and edible quality of the fresh fruit,affects the drying and processing quality of the fresh fruit,and seriously restricts the healthy development of the industry.The study on the law of fruit growth and development of Lycium barbarum L can provide theoretical reference for revealing the softening mechanism of Lycium barbarum L fruit in the process of pre harvest development or ripening.In this study,the fruit of Lycium barbarum L in different stages of growth and development was taken as the object.The physiological differences,the changes of microstructure and the proteomics of differences were studied in the process of fruit development.The softening mechanism of fruit in the process of development was discussed,and the softening nature of fruit was clarified,which provided theoretical basis for the softening regulation and quality improvement of Lycium barbarum L fruit.The specific research contents are as follows:(1)The analysis of physiological differences of Lycium barbarum L fruits in different growth and development stages showed that the ethylene release rate and respiratory intensity of the fruits increased sharply at 28 days,which confirmed that Lycium barbarum L belongs to respiratory climacteric fruit,with obvious physiological differences in different development stages;the hardness of the fruits increased first and then decreased with the growth stage,and the hardness of the fruits increased at 21 days At 35 days,the difference between the minimum and other periods was 20-30 times;the content of soluble solids increased all the time,and the change of polysaccharide content increased first and then decreased,reaching the maximum value at 28 days,and then decreased.It was found that the change trend of total acid,VC content,peroxidase activity and carotenoid were opposite at the mature stage;the change of total acid,VC content,peroxidase activity and carotenoid showed different trends Potential.(2)Compared with the microstructure of the cells in the fruits of Lycium barbarum L at different growth stages,it was found that on the 7th,14th and 21st day,the cells presented a transverse ellipse,arranged orderly and stacked tightly,gradually stretched from a square to a rectangle,and on the 28th and 35th day,the cells arranged loosely and deformed;compared with the cell wall structure,it was found that there were significant differences in different stages,and on the 7th day,the cell wall clearly showed a single shape After 14 days and 21 days,the cell walls became double-layer arrangement,and began to thicken.The cell walls were compact and layered.On 28 and 35 days,the cell walls were not easy to observe,the width was reduced to 1/2-1/3 of the original,and deformation occurred.(3)The results of cell wall component separation and extraction showed that the content of crude cell wall and cellulose decreased,while hemicellulose increased first,and then decreased rapidly after reaching the maximum in 21 days.The content of pectin(water-soluble pectin,covalent pectin and ionic pectin)decreased sharply in 28-35 days The results showed that rough cell wall,cellulose,covalent pectin and ionic pectin were significantly correlated with cell wall hardness(P<0.05).(4)Based on iTRAQ technology,the difference of protein identified in 7 days was compared with that in 14 days,21 days,28 days and 35 days respectively,and 1799 significant difference proteins were identified(P<0.05);through go function annotation,75 kinds of functional proteins related to fruit softening were screened,and KEGG was used to express different protein in different growth stages of Lycium barbarum L.It was found that carbohydrate metabolism in energy metabolism was the root cause of fruit softening.Energy metabolism increased the demand of cells for D-galactose andα-D-glucose.Starch,pectin and cellulose in cell wall were hydrolyzed by pectinesterase,α-galactosidase and cellulase to small molecular sugars,which participated in glycolysis,tricarboxylic acid cycle and glutaraldehyde interaction Phase transformation,fructose and mannose degradation,and pentose phosphate pathway lead to cell wall degradation and fruit softening.