Fruit Quality And Lignin Metabolism Of 'dangshan Su' Pear By Pollination

‘Dangshan Su'(Pyrus bretschneideri cv.Dangshan Su)is a kind of self-incompatible fruits with obvious xenia,which fruit quality is affected by pollination from different pear varieties to a great degree.Stone cells size and content is related to pear fruit quality,and it is one of the key factors affecting pear fruit quality.The stone cells are formed for the lignin deposited on the primary wall and the thickening of secondary wall.In this study,the materials were pear fruits of ‘Dangshan Su' pear pollinated with different varieties.The content of lignin and stone cell in pear fruit was determined and the effect of pollination on the lignin synthesis and formation of stone cell of pear fruit was compared.At the same time,analyze the differences in metabolism and proteins of‘Dangshan Su' pear pollinated by different varieties through the metabolome and proteome determining,clarify the effect of pollination on the metabolisms content and proteins expression in ‘Dangshan Su' pear fruit,regulate the content of stone cells in pear fruit,and improve the quality of pear fruit.The results are as follows:1.The change trends of the lignin and stone cells content,the stone cells area and numbers of ‘Dangshan Su' pear pollinated by different varieties at different developmental stages were basically the same,which was rising first and then decreasing.The different pollen varieties pollinated on ‘Dangshan Su' affected the lignin content and stone cells formation in pear fruits.There were significant differences in the lignin content,stone cells content,and the area and number of stone cells in pear fruit.The correlation coefficient showed that the stone cells content and stone cells area are positive correlation with lignin content.The regulation of lignin synthesis can change the formation of stone cells in pear fruit,thereby improved the quality of pear fruit.The stone cells content of ‘Dangshan Su'pear pollinated with ‘Wonhwang'(Pyrus pyrifolia ‘Wonhwang')at 145 days after pollination(DAPs)was lowest(0.2368±0.1627%).The quality of ‘Dangshan Su' pear pollinated with ‘Wonhwang' was better.2.GC-MS analysis showed that the metabolites were significantly changed in‘Dangshan Su' pear fruit pollinated by different varieties.The pear fruit of ‘Dangshan Su'pear pollinated with ‘Wonhwang' compared with ‘Dangshan Su' pear pollinated with‘Jingbaili'(Pyrus ussuriensis ‘Jingbaili'),at 47 DAPs,the sugar and amino acids contents were higher;the fatty acid content was lower.At 63 DAPs,the contents of sugar,amino acids and fatty acid were lower.At 102 DAPs,the sugar and fatty acid contents were higher,and the amino acids content was lower.The different pollen varieties pollinated on‘Dangshan Su' affected the contents of sugar,amino acid and fatty acid in pear fruit.The KEGG enrichment analysis of the differential metabolites showed that the KEGG pathway enriched by differential metabolites were not significantly at 63 DAPs and 102 DAPs;and31 KEGG pathways were significantly enriched at 47 DAPs,included the phenylalanine,tyrosine and tryptophan biosynthesis.Thus it can be seen that different pollen varieties pollinated on ‘Dangshan Su' not only affect the content of primary metabolites in pear fruits,but also affect the synthesis of lignin in pear fruits by regulating the synthesis of primary metabolites.3.The content of intermediate metabolites related with lignin synthesis process in‘Dangshan Su' pear pollinated with ‘Wonhwang' and ‘Jingbaili' were detected by targeted metabolome.The differential metabolites at 47 DAPs were p-coumaric acid,ferulic acid,sinapaldehyde,coniferyl alcohol and sinapyl alcohol.The differential significant metabolite at 63 DAPs was p-coumaric acid.The 47 DAPs was the main period of lignin synthesis in pear fruit.The pollination of different varieties had a greater influence on the content of p-coumaric acid.At 47 and 63 DAPs,the p-coumaric acid was significantly different,and the content of p-coumaric acid was positively correlated with lignin biosynthesis.4.Proteomic analysis showed that 233 proteins were identified as differentially expressed proteins between ‘Dangshan Su' pear pollinated with ‘Wonhwang' and‘Dangshan Su' pear pollinated with ‘Jingbaili'.Among these proteins,Pbr007161.1(CAD6)and Pbr035962.1(LAC4)were found to be related with lignin synthesis,and Pbr007161.1(CAD6),MSTRG.11809.4(BGLU15)and Pbr022326.1(PER47)were involved in the phenylpropanoid pathway.It can be seen that after ‘Dangshan Su' pollinated with different pear varieties,the lignin synthesis and the stone cells formation in pear fruits were regulated by affecting the expression levels of CAD6,PER47,BGLU15 and LAC4.