Effect Of Calcium On Fruit Quality And The Formation Of Stone Cell In Nanguo Pear

Nanguo pear is one of the special fruits in Liaoning Province.It has the characteristics of rich fruit aroma and strong cold resistance.However,because the fruit contains more stone cells,it seriously affects the fruit quality.Calcium is an essential nutrient for plants,involved in the determination of cell fate and cellular signaling pathways.In this study,Nanguo pear was used as the experimental material,and different kinds of exogenous calcium were used to treat the young fruit of Nanguo pear.The fruit quality,calcium content,stone cell and lignin content and lignin synthesis related genes of Nanguo pear after calcium treatment were analyzed.Changes in expression,combined with lanthanum chloride treatment,study the relationship between calcium signaling and lignin polymerization in pear fruit.The purpose is to determine the regulation of calcium in the development of pear fruit cells.The main findings are as follows:1.After the flowering period of Nanguo pear and the flowering stage for 20 days,different concentrations of calcium chloride and sugar alcohol chelated calcium were sprayed.The fruit quality index of Nanguo pear was lower than single fruit weight,horizontal and vertical diameter,soluble solids and hardness.In the control,the calcium-treated stone cells were lower than the control,and the total calcium content of the fruits treated by the calcium preparation was higher than that of the control.On the whole,the effect of spraying 5 g·L-1 CaCl₂ after 20 days of full bloom was better than other treatments.It is the best application scheme for the calcium preparations selected in this study to improve the quality of Nanguo pear.2.Further research indicated that after 20 days of full bloom of Nanguo pear,5 g·L-1 CaCl₂ was sprayed,and the stone cell and lignin content of the fruit were lower than the level of control at different developmental stages,the results of histochemical localization of lignin are consistent with the lignin content.At the late stage of fruit development,the calcium content gradually decreased,and the calcium content of Nanguo pear after calcium treatment was higher than that of the control.At the same time,the expression levels of related genes of lignin catabolism in stone cells during fruit development were detected.It was found that the expression levels of PAL,CAD,POD were significantly down-regulated after calcium treatment,and HCT and CCR were notably up-regulated.3.In order to verify the relationship between calcium signaling pathway and fruit lignin metabolism,the lignin metabolism of Nanguo pear under in vitro conditions was studied by La Cl3 treatments.The results showed that the lignin contents of the fruit after treatmenting with the La Cl3 was significantly lower than that of the control.The CDPK9 gene remarkably down-regulated,meanwhile,the activities of NADPH oxidase decreased,and the H2O2 content significantly decreased,and the hydrogenochemical histochemical localization and H2O2 content were consistent,indicates that the blockage of calcium signal can interfere with the polymerization process of lignin by affecting ROS metabolism.In this study,5g·L-1CaCl₂ was screened for fruit quality and stone cell accumulation.Preliminary study on the mechanism of calcium regulation of fruit lignin metabolism,it has important guiding value for controlling the reduction of stone cell content and improving fruit qualities.