Expression Of BHLH04G And BHLH06G Transcription Factor In E.coli And Their Effects On Saponin Synthesis And Nodulation In Soybean

Transcription factors play an important role in the regulaion of gene expression and bHLH transcription factor family is the second largest transcription factor family.A lot of bHLH transcription factors in Arabidopsis have been reported.Soybean is an important crop,and research on metabolic regulation has important significance for improving the quality traits of soybean.This experiment is on how bHLH04 G and bHLH06 G affect nodulation and soyasaponin synthesis.On the one hand,the expression vectors of both genes were constructed for expessing in E.coli,respectively.SDS-PAGE analysis indicated that both proteins were highly expressed but they were in the form of inclusion bodies.Even under different induction conditions and in different expression vectors,the protein still only exists in the form of inclusion bodies and no significant amount of soluble protein was detected On the other hand,we constructed RNAi vector for generating transgenic soybean hairy roots.The number of nodules was significantly reduced and the expression of nodulation-associated genes decreased in RNAi transgenic hairy root.In addition,the expression level of AMS decreased in RNAi transgenic hairy root.GC-MS analysis indicated that the amount of soyasapogenol B,C and E were also reduced.In order to further clarify the regulation mechanism of these two transcription factors on the synthesis of soybean saponin and nodulation and nitrogen fixation,RNAi-AMS vector was constructed to cultivate the transgenic hairy roots.The expression of nodulation related genes and the nodule number were both decreased.Therefore,we hypothesized that AMS also positively regulates nodulation and nitrogen fixation in Soybean.