| Sweet cherry（Prunus avium）is a popular fruit due to its delicious taste,bright color,and rich nutritional value.In recent years,the planting area of sweet cherry in China has rapidly increased to 230,000 ha.This increase has been essential in increasing farmers’income and revitalizing rural areas.However,the fruit maturity of a single tree is not consistent in the production of sweet cherry.This inconsistency leads to the consumption of much labor in the process of picking,which hinders the development of the cherry industry.This study investigated the physiological and molecular effects of exogenous abscisic acid（ABA）on sweet cherry fruit quality and maturation,systematically examining ABA’s impact on sweet cherry ripening and proposing an ABA application strategy for regulating sweet cherry maturity to support the cherry industry.Sweet cherry varieties‘Rabins’and‘Luying 3’were treated with 400 mg·L-1 ABA,and the physiological changes in the fruit were analyzed.Transcriptome sequencing was conducted on‘Luying 3’fruit using high-throughput sequencing technology,followed by functional enrichment analysis of differentially expressed genes.Differentially expressed genes and AP2/ERF transcription factors influenced by ABA were identified from the sequencing results,and their expression levels in response to ABA treatment were analyzed using real-time PCR.The main findings include:（1）Exogenous ABA(400 mg·L-1)enhanced the color of‘Rabins’and‘Luying 3’fruits at47 days post-flowering,increasing fruit size and individual fruit weight.The individual fruit weight of‘Rabins’and‘Luying 3’increased by 9.62%and 5.98%,respectively.However,there was no significant effect on fruit size,average single fruit weight,soluble solids,titrable acid,and sugar-acid ratio of‘Rabins’and‘Luying 3’at 54 days post-flowering.（2）To investigate the impact of exogenous ABA on endogenous plant hormones,endogenous hormone levels in‘Rabins’and‘Luying 3’fruits were measured at each ripening stage.It was found that under the influence of exogenous ABA,the endogenous auxin of‘Rabins’increased by 177.97%and 12.09%at 47 and 54 days after flowering,while that of‘Luying 3’decreased by 42.77%and 45.34%at 47 and 54 days after flowering,respectively.Endogenous ABscisic acid in‘Rabins’and‘Luying3’increased by 58.21%and 70.34%47 days after flowering,and decreased by 81.65%and 20.94%54 days after flowering,respectively.Endogenous gibberellin increased by 178.13%and 601.37%47 days after flowering in‘Rabins’and‘Luying 3’,respectively.The content of endogenous salicylic acid in‘Rabins’decreased by64.08%47 days after flowering,and increased by 134.46%54 days after flowering.The content of endogenous salicylic acid in‘Luying 3’increased by 7.88%and 24.45%47 and 54 days after flowering,respectively.（3）Transcriptome sequencing and differential expression analysis of‘Luying 3’genes identified 766 differentially expressed genes（DEGs）in response to ABA,including 553 up-regulated genes and 213 down-regulated genes.DEGs were significantly enriched in the KEGG database,including plant hormone signal transduction pathway,MAPK plant signal transduction pathway,and glycolysis pathway.（4）Exogenous ABA induced Pav ABF2,Pav PR1,Pav ETR,Pav TCH4,Pav PP2C,and Pav EBF1＿2 to mediate endogenous hormone synthesis,affecting fruit ripening.Pav ADH1,Pav ADH5,Pav ALDH,and Pav ALDO genes were up-regulated by ABA,positively regulating sweet cherry fruit metabolic rate and influencing fruit ripening.（5）The expression levels of Pav AP2-1,Pav AP2-2,Pav AP2-3,and Pav AP2-4 genes increased with sweet cherry fruit ripening.Pav AP2-5 and Pav AP2-6 significantly affected sweet cherry fruit ripening around 47 days post-flowering.Pav AP2-7 and Pav AP2-8 genes regulated sweet cherry fruit ripening before 40 days post-flowering.Exogenous ABA promoted the expression of certain Pav AP2 transcription factors during sweet cherry ripening while inhibiting others.（6）Based on the physiological and molecular regulation results of ABA on sweet cherry fruits,an ABA application strategy for regulating sweet cherry ripening consistency was proposed.Applying exogenous ABA(400 mg·L-1)during the color transformation stage could synchronize fruit ripening,allowing for a single harvest and reduced picking costs.Future research should explore ABA’s effects on other sweet cherry varieties and investigate alternative hormones for regulating sweet cherry maturity to enable industrial application. |
