Effect Of Naringenin And Gene RHE_RS01180 Of Rhizobium Etli CFN42 For The Symbiotic Island Horizontal Transfer In Azorhizobium Caulinodans ORS571

Rhizobium could symbiotic with leguminous plant through form nodules and nitrogen fixation?A.caulinodans ORS571 could forming stem nodules on it shost Sesbania rostrata and it has higher nitrogen fixation efficiency compared with root,in A.caulinodans ORS571,has a 87.6kb symbiotic island which contains three nodulation loci that are involved in the biosynthesis of Nod factors and tre genes involved in it transfer.The symbiotic island could be transferred to different rhizobium genus through resection,cyclization,conjugation.the receptor bacterium acquire the ability to nodule with new host Sesbania rostrata after accepting the symbiosis island.which not only improves the efficiency of nodulation and nitrogen fixation,but also expands rhizobium host range.In the process of the transfer of symbiotic islands,the naringenin of flavonoids can increase the frequency of island transfer,about 10-20 folds.However,in the previous study of our laboratory,we found some rhizobium can accept the symbiotic island(such as Mesorhizobium huakuii 93),but some rhizobium which could not accept symbiosis island(Rhizobium etli CFN42),so we guess whether the rhizobium coundn't accept symbiosis island contain a gene inhibits it accept symbiotic islands.In this study,the mutant library of CFN42 was established by transposon insertion inactivation,and R.etli CFN42 could accept symbiotic island was screened by the conjugation of mutant sub-library with the A.caulinodans ORS 571.Then we use the method of arbitrarily PCR to get the position where the transposon and symbiotic island was inserted,the symbiotic island was inserted to a specific site of gly-tRNA gene and the transposon into the RHE_RS01180 gene and located upstream of RHE_RS01175,By alignment in NCBI,RHE_RS01180 is a transcriptional regulatory factor of the XRE family,And related with morphology of differentiation,self-drug resistance,heterogeneous material regulation and other functions in microbiology,its function has not been studied.RHE RS01175 belongs to the restriction endonuclease HsdR,have the function of Restrict foreign genes,So we speculated that R.etli CFN42 could accept symbiosis island may be due to the inactivation of RHE_RS01180,or it may be other reasones like inserted in the RHE_RS01175 upstream,influncing the RHE RS01175 expression or breaking the RHE_RS01175 promoter,inhibition the expression of RHE_RS01175.Therefore,this study knockout,covering,and overexpression the RHE_RS01175 and RHE_RS01180,found that no matter knockout or overexpression the RHE_RS01175 gene in R.Ketli CFN42,it can not make accept symbiotic island,it description that the gene of RHE_RS01175 is independent of R.Ketli CFN42 can accept symbiotic island.but after RHE_RS01180 knockout,R.etli CFN42 can accept symbiotic island,and the the transfer frequency were about 10-7.Then we do an Covering the experiment found that it was not able to accept the symbiotic island,therefore,we believe that the gene of RHE_RS01180 is associated with whether R.etli CFN42 can accept the symbiotic island.In this study,we also studied whether it influences the growth and nodules after the knockout of RHE_RS01175 and RHE_RS01180,we found that 28 ? in CY medium RHE_RS01175 deletion was consistent with WT growth,but RHE_RS01180 deletion was slower than WT,so after knockout RHE_RS01180,R.etli CFN42 growth was inhibited.In the nodulation,the RHE_RS01175 and RHE_RS01180 deletion compared WT no difference,but the number of tumor bacteria RHE_RS01180 compared with WT less,guess because of the Growth defects is revealed in the symbiosis with leguminous plants.