The Mechanism Of BR Regulates Soybean Nodulation

As a kind of Legumes,soybean(Glycine max)can form symbiotic relationship with nitrogen-fixing rhizobial bacteria.This occurs within specialized root organs called nodules that provide the conditions required for nitrogen fixation,which enable the soybean to grow in nitrogen poor soil.As a group of plant specific steroidal hormones,Brassinosteroids(BRs)have been shown to involve in the regulation of soybean nodulation.However,there is still little known about the role of BRs in soybean nodulation.In this study,we would like to shed light on the mechanism of BRs regulate soybean nodulation by using a series of physiology and biochemistry experiment.The results are as follow:1.The establishment of BR marker gene system in soybean.We analysis the homologous genes of BR synthesis key enzyme CPD and CYP90D1 by using bioinformatic method.We found that their homologous genes can also be feedback regulated by BR signaling through qRT-PCR assay.2.Exogenous application assay reveals that BR can inhibit soybean nodulation and decrease nitrogenase activity.3.BR inhibit nodulation signaling.We measured the expression of nodulation induced genes through qRT-PCR assay,and we found that exogenous application of BR can inhibit nodulation signaling output.4.BR inhibit nodulation signaling through BR signaling pathway.We analysis the homologous genes of BR signaling pathway key transcription factor BES1 by using bioinformatic method and named GmBES1 L.By using the hairy-root transformation soybean,we found that over-expression GmBES1L-D can inhibit soybean nodulation and decrease nitrogenase activity.