The Regulatory Effect Of Chitosan Coating On Extrusion Damage Of Korla Pear And Its Omics Analysis

Korla pear with rich aroma,tender and juicy is one of the most representative characteristic agricultural products in Xinjiang.Korla pear is vulnerable to mechanical damage during storage and transportation after harvest,which seriously affects product quality and sales value.It is of great significance to study the regulation technology and mechanism of mechanical damage of Korla pear for extending its shelf life and increasing its commodity value.In this paper,the effects of chitosan coating on the storage quality of Korla pear were studied,and the transcriptomes and non-targeted metabolomics were used to explore the key signaling pathways of the regulation of chitosan coating on the storage quality of Korla pear after extrusion injury,providing theoretical basis for the mechanism and regulation strategies of post-harvest extrusion injury stress of Korla pear.The main conclusions are as follows:（1）Extrusion damage accelerated the process of respiration and quality degradation of Korla pear during storage,which showed that hardness and soluble solids decreased.Chitosan coating significantly inhibited the injured respiration of the pear,and the respiratory intensity of the coating day was reduced by5 mg·kg^-1·h^-1compared with the injured group.It also delayed the quality decline of damaged fruits and improved the antioxidant activity of fruits.The total phenol content,OH^-and O₂^-clearance rates were significantly higher than those in the injured group,showing a better regulation effect on the extrusion damage of fragrant pear.（2）Transcriptomic analysis showed that there were 756 different genes between the crush injury group and the control group,419 of which were up-regulated.By regulating PCO2,GAD,SDH,CKX6,CYP85A and other genes,the metabolism of taurine and hypotaurine,metabolism of alanine,aspartic acid and glutamic acid,glucose and other signaling pathways were affected in the crush injury group,so as to enhance the fruit’s resistance to injury stress.There were 422 different genes in the injured coating group and the injured group,among which 353 genes were up-regulated.After chitosan coating,differential genes such as CML3,ATPA and PMA1 participate in the damage regulation process of pear through RNA degradation,oxidative phosphorylation and galactose metabolism signaling pathways.（3）Metabolome analysis showed that there were 29 different metabolites between the injured group and the control group,of which 15 were up-regulated.The contents of citric acid,isocitrate and gamma-aminobutyric acid were significantly decreased,while the contents of secondary metabolites such as peach leaf corallin,3-O-p-coumaryl quinic acid and polyaminoannonone were increased.The response to the stress of peach pear was through TCA cycle,metabolism of alanine,aspartic acid and glutamic acid,and metabolism of butyric acid.Among the 28 different metabolites between the damaged coating group and the damaged coating group,18 were up-regulated.The contents of metabolites such as propyl gallate,esicrin and allicin increased significantly,while the content of jasmonic acid decreased.Chitosan coating may reduce the stress response of damaged pear by affectingα-linolenic acid metabolism and plant hormone conduction,and play a positive role in regulating the quality of damaged pear.（4）Transcriptome and metabolome association analysis showed that there were significant correlations between the genes and metabolites of the damaged and control groups,and between the damaged and coated groups.The differential genes and metabolites of the injured group and the control group were annotated to the TCA cycle and amino acid metabolism pathway,through the up-regulation of LTA3,ALDH5F1,PAO1,GAD,down-regulation of GDH1,At1g50460,TRPA1,and the reduction of the content of metabolites such as citric acid,isocitrate,γ-aminobutyric acid,etc.In response to compressive damage stress.Both the damage coating group and the damage group were co-annotated to Alpha linolenic acid metabolism and plant hormone signaling pathways.The expressions of 4CLL5,LOX3.1,LAX2,MYC2,IAA27 and TGA7 were upregulated and the content of jasmonic acid was decreased,which may reduce the stress effect of extrusion injury and delay the quality decline of damaged pear.