Study On The Correlation Between Split Fruit And Main Fruit Characters Of Different Split Sweet Cherry Varieties

The cracking of sweet cherry before ripening has always been one of the bottleneck factors affecting the fruit quality and economic benefit.In this study,two sweet cherry varieties with different cracking characters,‘Tieton’ and ‘Mingzhu’,were used as test materials to study the changes of fruit agronomic characters,nutrients and related enzyme activities during natural development and before and after cracking.Transcriptome sequencing was used to screen the high-expression genes associated with fruit cracking,which were verified by fluorescence quantitative PCR.The results are as follows:1.The fruit cracking of sweet cherry is related to the developmental stage,fruit mechanical characteristics and fruit shape index.The growth rate of cross,longitudinal,side diameter and single fruit weight of ‘Tieton’,a variety prone to cracking,was higher than that of ‘Mingzhu’,a variety resistant to cracking.Fruit cracking was positively correlated with fruit diameter,hardness and single fruit weight,among which,it was positively correlated with fruit diameter and negatively correlated with epidermal toughness.It has nothing to do with longitudinal diameter,lateral diameter or fruit shape index.2.The results of water immersion test showed that water absorption of sweet cherry resulted in fruit cracking and was positively correlated with fruit maturity.The fruit cracking rate increased with the increase of fruit maturity,the water absorption and fruit cracking rate were the lowest at the white stage,and the highest at the mature stage.The water absorption and fruit cracking rate of ‘Tieton’ were higher than that of ‘Mingzhu’.3.Compared with normal fruits,the contents of calcium,pectin,free glucose and free fructose in fruit of ‘Tieton’ and ‘Mingzhu’ decreased,while the contents of protein,potassium and free fructose in fruit peel increased.‘Tieton’ calcium,pectin,protein,potassium,free fructose,free glucose content is lower than ‘Mingzhu’.4.Compared with normal fruit,the contents of cellulase,polygalacturonase,pectin lyase and β-gal in fruit peel of ‘Tieton’ and ‘Mingzhu’ increased,while the contents of β-galactosidase in fruit pulp decreased.The contents of cellulase,polygalacturonase,pectin lyase and β-galactosidase of ‘Tieton’ a variety prone to cracking,were higher than those of ‘Mingzhu’,a variety resistant to cracking.5.In the transcriptome data,3953 differentially expressed genes were screened from the normal fruit of the fissure prone variety ‘Tieton’ compared with the normal fruit of the fissure resistant variety ‘Mingzhu’,among which 1592 up-regulated genes and 2361 down-regulated genes.A total of 2119 differentially expressed genes were detected in crack tolerance varieties,among which 1072 genes were up-regulated and1047 genes were down-regulated.A total of 1941 differentially expressed genes were detected in the split fruit of the easily cracked varieties compared with the normal fruit,among which 777 up-regulated genes and 1164 down-regulated genes were detected.A total of 2254 differentially expressed genes were detected in the cracked fruit of crack tolerant varieties compared with normal fruit,among which 1344 upregulated genes and 910 down-regulated genes were detected.Eighteen differentially expressed genes enriched in gene function and KEGG metabolic pathway were screened out,and their expression levels were verified by fluorescence quantitative PCR,which was consistent with transcriptome sequencing results.