Effects Of Bagging On Sugar, Acid, Lignin Metabolism And Development Of Stone Cells On Pear Fruit

Pyrus bretschneideri cv. is a pear variety of the largest cultivated area, which loved by comsumers. However, due to the degradation of Pyrus bretschneideri cv. varieties in recent years, the result is that the stone cell content increased and the sugar content reduced, it has seriously affected the fruit flavor and quality of Pyrus bretschneideri cv..Bagging can not only improve the appearance quality of the fruit significantly, but also can have an effect on the intrinsic quality of the fruit, such as soluble sugars, organic acids, stone cell content and so on. In this article, using bagging Pyrus bretschneideri cv. fruit as main materials, the changes in stone cells, lignin, sugars and organic acid contents were analyzed, and also the changes in the activity of the enzymes that related to the metabolism of lignin, sugar and organic acid were analyzed. In order to explore the effects of bagging on the development of stone cell and lignin metabolism of Pyrus bretschneideri cv., and the changes in the accumulation of sugar and organic acid. And then to discuss the effects of sugar and organic acid metabolism to lignin metabolism and the development of stone cells, and to reveal the reason of the result that the bagging pear has less stone cell content. Providing the theoretical basis to reduce the content of stone cell and improve fruit quality of Pyrus bretschneideri cv. by bagging.The main research results are as follows:1. After bagging, the contents of glucose, fructose and sucrose in ripe fruit of Pyrus bretschneideri cv. increased respectively by2.8%,3.7%and11.4%, the content of titratable acid reduced by15.4%, the sugar-acid ratio increased by18.1%, the contents of stone cell and lignin reduced respectively by31.6%and13.9%. The quality of fruit was improved.2. It was reduced that the distribution of sclereids after bagging, and the number of sclereids reduced by28.0%, and the diameter of sclereids reduced by45.8%.3. During the period of the formation of stone cells, a large number of lignin was synthesized. The lignin content was significantly correlated to the content of stone cell. After bagging. the activity of Phenylalanine ammonian-lyase (PAL). Cinnamate-4-hydroxylase (C4H) and4-Coumarate:Coenzyme A ligase (4CL) were restrained, which are enzymes related to lignin metabolism. The contents of cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid and sinapic acid were reduced, which are lignin intermediate metabolites. As multiple regression analysis showed, there is linear relationship between the lignin content and p-coumaric acid content, p-coumaric acid is closely related to lignin synthesis. The restraint of the activity of lignin synthesis enzymes and the lack of lignin intermediate metabolite impacted on the lignin synthesis and the development of stone cells.4. After bagging, the activity of Acid invertase (AI), Neutral invertase (NI) and Sucrose Synthase (SS) were restrained, which are enzymes related to sucrose metabolism. These enzymes could not catalyze more sucrose into hexose as the source of carbon. The contents of malic acid and citric acid were reduced in bagged fruit, and the activity of Malic enzyme (ME) and Phosphoenolpyruvate carboxykinase (PCK) were restrained, which are enzymes related to organic acid metabolism. These enzymes could not catalyze more organic acid into sugars that involved in lignin anabolism. Multiple regression analysis showed that, the contents of fructose, malic acid and citric acid were significantly correlated to the content of lignin. The sugar and organic acid metabolism were restrained and the carbon source of lignin synthesis was reduced after bagging. Influencing the synthesis of lignin.5. Bagging can reduce the carbon skeletons involved in lignin synthesis and restrain the activity of enzymes related to lignin metabolism in Pyrus bretschneideri cv.. Thereby reducing the synthesis and deposition of lignin, thus affecting the development of stone cells.