Preliminary Study On The Function Of Apple Transcription Factor MdHB1 In GA Synthesis

Transcription factors play important roles in all stages of plant growth and development,and they are involved in signal transduction of multiple hormones.MdHB1 is a member of HD-Zip transcription factors.In this study,MdHB1-overexpressing tobacco(‘NC89')and apple(‘Granny Smith')flesh ofvirus-induced gene silencing(VIGS)were used as the experimental materials for investigating the effects of MdHB1 on gibberellin(GA)synthesis.During this time,MdHB1 was expressed in Escherichia coli(E.coli)and its polyclonal antibody was prepared by immunization in New Zealand rabbits.The main results were as follows:(1)The MdHB1 gene was cloned into pGEX-6p-1 and pET-28a(+),transferred into E.coli competent cells BL21(DE3).Induced by isopropyl-?-D-thiogalactoside(IPTG),MdHB1 fusion protein taggedGST or 6×His tagged were obtained.The fusion protein MdHB1-His6 was purified by Ni-NTA,which was subsequently used to prepare polyclonal antibody by immunization of rabbits.Enzyme-linked immunosorbent assay(ELASA)showed the antibody titer was high.Western blot assays showed that the MdHB1 protein can be successfully detected from the total protein ofE.coliandapple young leaves.It is shown that the polyclonal antibody can be used for further protein research,and digging into the function of MdHB1 in plants.(2)Treated by gibberellin synthesis inhibitor paclobutrazol(PAC),the protein level ofMdHB1 in the applefleshrose significantly,which indicated that MdHB1 might played a role in the signal transduction of gibberellin(GA);InMdHB1-overexpressingtobacco,the expression levels of NtGA20ox1 and NtGA2ox1 were decreased,while NtGA3ox1 increased obviously.InMdHB1-silencing apple flesh,the transcription level of MdGA3 oxwashigher than control,so was the content of GA3.It was speculated that MdHB1 was involved in the signal transduction of gibberellin.