Screening of plant growth promoting bacteria (PGPB) from rhizosphere and bulk soil of Caragana microphylla in different habitats and their effects on the growth of Arabidopsis seedlings

Abstract

The rhizospheric bacterial community associated with desert shrub is an important part of sandy land ecosystems. In this study, we isolated and characterized culturable bacteria associated with Caragana microphylla from a wide range of habitats in North China. We chose five habitats with different aridity index values and dune types. In both trials, soil physicochemical parameters and culturable bacterial populations showed the rhizosphere effects. The culturable bacterial communities of rhizosphere and bulk soil were determined using 16s rDNA sequencing. We identified that the proportions of beneficial bacterial strains with plant growth promoting (PGP) traits (nitrogen fixation, phosphate solubilization and indole acetic acid production) were significantly greater in rhizosphere soil than in bulk soil. Some of the strains screened in this study had significant effects on the growth of Arabidopsis seedlings. These effects included inhibiting the elongation of primary roots, promoting lateral root formation and increasing the shoot fresh weight. In conclusion, our study provides a comprehensive survey of the culturable bacterial populations of the rhizosphere in C. microphylla habitats and identifies potential PGPBs that may help develop an efficient revegetation strategy to manage desert land.