Genetic diversity of the Rhizobia and screening of highefficient growth-promoting strains isolated from Sesbania cannabina in Rudong County

Abstract:

Abstract:［Objective］To study the genetic diversity and phylogeny of Rhizobia isolated from Sesbania cannabina growing on the tidal flat in Rudong County and screen high-efficient growth-promoting strains as Ｒhizobia inoculator to S．cannabina．［Methods］Phylogenetic analyses were based on 16S rRNA gene，housekeeping genes (recA，atpD，glnII) and symbiotic genes (nodA，nifH)．The growth-promoting efficiency was tested by plant inoculation assay on S．cannabina in greenhouse．［Results］ The 32 isolates belonged to Ensifer，Neorhizobium，Rhizobium，and most closely related to E．meliloti，N． huautlense，R．pusense．The phylogenies of nodA and nifH were congruent，and most closely related to E. saheli． The 7 representative isolates were resistant to high concentration of NaCl (5%，W/V)，and YIC5082 grew well in TY medium with 6% NaCl．In plant inoculation assay，all the 7 representative isolates were effective on symbiotic nitrogen fixation，and 6 out of the 7 isolates significantly enhanced the fresh weight and height of plants．［Conclusion］Ｒhizobia isolated from S．cannabina growing on the tidal flat in Ｒudong County showed rich genetic diversity． N．huautlense and E． meliloti were the dominant species．Most of the isolates showed fine growth-promoting efficiency and salt tolerance．YIC5077 showed the best growth-promoting efficiency，good nodulation and nitrogen fixation abilities，which has promising potential applications as Ｒhizobia inoculator to S. cannabina．

Key words:Keywords: Rudong，S.cannabina Rhizobia，16S rRNA gene，housekeeping genes，genetic diversity，high-efficienct growth-promoting isolates