Characterization of rhizospheric microbial flora of Hunyuan Astragali Mongolici Radix by ARISA fingerprinting Effects of continuous potato cropping on the diversity of soil microorganisms Impact of root exudates from transgenic plants on soil micro-ecosystems Advances in studies on rhizospheric microorganism of medicinal plants Correlation between distribution of rhizospheric microorganisms and contents of steroidal saponins of Paris polyphylla var. yunnanensis Co-metabolic and synergic phenol-degradation mechanisms of Eichhornia crassipes and its rhizospheric microorganisms