Regulations Of Ethylene Synthesisby ABA-Regulated Transcription Factors During Tomato Fruit Ripening

The plant hormones ethylene and abscisic acid(ABA)play an important role in the regulation of tomato fruit ripening.Related studies have shown that ABA may promote tomato fruit ripening by regulating ethylene biosynthesis,but the specific regulation mechanism is still unclear.In this study,cherry tomato fruits in mature greenstage were used as experimental materials,and the isolated mature green tomato fruits were treated with exogenous ABA.On the basis of clarifying that ABA promotes the postharvest ripening of tomato fruits,RT-q PCR technology was used to analyze the gene expression changes of ABA-related and ethylene synthesis-related transcription factors and key enzyme-encoding genes in the synthesis pathway identified in the group data during postharvest storage,and the ABA-related transcription factor-encoding genes and ethylene synthesis-related genes were cloned.The promoter sequence of the gene was used to explore the regulatory relationship between ABArelated transcription factors and ethylene synthesis-related gene promoters by yeast one-hybrid and dual-luciferase techniques.The research results provide data for clarifying the hormone interaction regulatory network during tomato fruit ripening refer to.The main research results of this paper are as follows:(1)Exogenous ABA treatment can promote the postharvest ripening process of green ripe tomato fruits.During the 16-day storage period after treatment,compared with the control treatment(CK),exogenous ABA treatment could increase the endogenous ABA content and ethylene release rate in tomato fruits,accelerate the appearance of ethylene transition peak,and promote the ripening of tomato fruits process,and ABA treatment promoted the color development and firmness of the fruit,increased the content of soluble sugar and accelerated acid metabolism during the ripening process,and promoted the texture change and the accumulation of flavor substances during the ripening process of tomato fruit.(2)ABA treatment can regulate the expression of ABA-related transcription factors(Sl ABF,Sl ABI5-2-1 and Sl ABI5-2-2)and ethylene synthesis-related genes(ACO1,ACS2,ACS4,NOR,CNR,etc.)during tomato fruit ripening Express.Based on the previous transcriptome data of the research group,three ABA-related transcription factors Sl ABF,Sl ABI5-2-1,and Sl ABI5-2-2 were successfully cloned.RT-q PCR analysis results showed that they were all expressed in tomato fruit development and ripening stages.Moreover,ABA treatment can down-regulate the transcription level of Sl ABF,and up-regulate the transcription level of Sl ABI5-2-1 and Sl ABI5-2-2.The evolutionary numbers show that the three transcription factors are clustered with the ABI5 family,and bioinformatics analysis shows that they all conform to the b ZIP family Transcription Factor Characteristics.At the same time,ABA treatment significantly up-regulated the expression of key enzyme coding genes(ACO1,ACS2,ACS4)in the ethylene synthesis pathway during tomato fruit ripening,and up-regulated the expression of transcription factors Sl FUL1,Le MADS-RIN,Sl TAGL1,NOR,and CNR genes related to ethylene synthesis.The down-regulation of Sl MADS1 gene expression indicated that ABA played an important role in regulating the expression of ethylene synthesis-related genes during tomato fruit ripening.(3)The results of molecular interaction analysis showed that Sl ABI5-2-2 binds to the ABRE element on the ACS2 gene promoter,and Sl ABI5-2-2 can inhibit the transcription of ACS2.By analyzing the promoter sequences of genes related to ethylene synthesis,it was found that all of them contained ABRE elements.Sl ABF,Sl ABI5-2-1,and Sl ABI5-2-2transcription factors and the promoter sequences of genes related to ethylene synthesis were screened by yeast one-hybrid technology,and it was found that Sl ABI5-2-2 could interact with the ACS2 gene promoter ABRE elements interact,and further double luciferase experiments prove that Sl ABI5-2-2 can inhibit the transcription of ACS2.