Screening Of Transcription Factors Regulating Tomato Abscission-related Polygalacturonase

The yield of tomato was seriously affected by abiotic stress,which resulted in flowering and fruit drop.Previous studies have reported that Tomato abscission related polygalacturonase(TAPGS)plays a major role in the expression of various hydrolases during Tomato abscission.In this study,the promoters of SlTAPG1,SlTAPG2 and SlTAPG4 were firstly analyzed by bioinformatics.The upstream of the transcription start site at 400 bp contained multiple MYB and BHLH(MYC)binding sites,and SlTAPG1 was confirmed by the isolated expression of GUS reporter gene.The 400 bp promoter of SlTAPG2 and SlTAPG4 can drive the expression of polygalacturonase.Then,the promoter of SlTAPG1,SlTAPG2 and SlTAPG4 was used to construct bait yeast,and the upstream genes were screened to obtain multiple transcription factors.Soly C01G057910(SlMYB2)was detected in SlTAPG1,SlTAPG2 and SlTAPG4 screening with high frequency by comparing the results of the screening database.Through yeast single hybridization point-to-point verification,it was found that the promoter of SlTAPG1,SlTAPG2 and SlTAPG4 could be bound by SlMYB2,and the gene was localized in the nucleus.The silencing results showed that SlMYB2 gene could delay the deletion,and the higher the silencing efficiency,the stronger the ability to delay the deletion,and the outliers SlTAPG1,SlTAPG2 and SlTAPG4 expression levels were also matched with the deletion rate.In addition,ethylene treatment can increase the expression of SlMYB2 and promote the occurrence of shedding.Auxin treatment can inhibit the expression of SlMYB2 to a very low level,and almost completely inhibit the exfoliation of tomato flower stalk.In this study,we found a transcription factor,SlMYB2,which is regulated by ethylene and auxin,and regulates flowering and fruit dropping by regulating the transcriptional activity of polygalacturonase during flowering of tomato.A key gene,SlMYB2,involved in the synthesis pathway of tomato hydrolase during abscission was revealed from the direction of transcriptional regulation.This study laid a solid foundation for exploring the new mechanism of regulating flowering and fruit drop of tomato.