Study On The Regulation Of Ethylene Synthesis In Nanguo Pear Fruit By Brassinolide

Ethylene production during fruit ripening is an important factor affecting fruit storage time.Studying ethylene change during fruit ripening is of great significance for artificial control of fruit storage.'Nanguo' pear(Pyrus ussuriensis)is a kind of pyrus ussuriensis,which is a typical climacteric fruit.Fruit ripening is affected by ethylene regulation,temperature and hormone.In recent years,it has been reported that brassinolide can regulate the synthesis of ethylene,but the molecular mechanism is still not clear.In this study,"Nanguo " pear was used as the test material,and the following conclusions were obtained by the treatment of 2,4-Epibrassinolide instead of brassinolide:1.Compared with the control fruit,the ethylene production of EBR treated fruits with 3.0 ?M was significantly decreased.2.After EBR treatment,the expression of Pu BZR1 increased significantly,the expression of PuACO1 gene was significantly reduced.The expression of Pu ERF2 was significantly reduced.There were no changes in the other three ERFs.There was no change in the expression of ACS,a key enzyme in ethylene synthesis pathway.Referring to the pear genome,we have cloned the important transcription factor Pu BZR1 of BR signal transduction pathway,the key enzyme Pu ACO1 of ethylene synthesis pathway and Pu ERF2 of ethylene signal transduction pathway.3.Yeast one hybrid and EMSA test found that PuBZR1 could be combined with the promoter of Pu ACO1 and found Pu BZR1 negatively regulated Pu ACO1 through the GUS reporter gene.4.Yeast one hybrid and EMSA test found that Pu ERF2 could be combined with the promoter of Pu ACO1 and found that Pu ERF2 was positively regulated the promoter of Pu ACO1 through the GUS reporter gene.5.Yeast one hybrid and EMSA test found that Pu BZR1 could combine the promoter of Pu ERF2 with the GUS reporter gene to detected Pu BZR1 negatively regulated Pu ERF2 transcription.6.Through yeast two hybrid test and Pull-down test,it was found that there was protein interaction between Pu BZR1 and Pu ACO1.The above results showed that Pu BZR1 inhibited the promoter activity of Pu ACO1 and the negatively regulated transcription of Pu ACO1;Pu BZR1 negatively regulated Pu ERF2 and inhibited the transcription of PuACO1;This experiment explained the mechanism of EBR inhibiting ethylene synthesis in 'Nanguo' pear from molecular perspective,and has important practical significance for artificial regulation and control of fruit storage.