Analysis of bacterial communities in rhizosphere soil of healthy and diseased cotton (Gossypium sp.) at different plant growth stages

Bacterial communities in rhizosphere soil of healthy and diseased cotton (infected by the pathogenic fungus Verticillium dahliae Kleb.) were examined at different plant growth stages using T-RFLP and 16S rDNA clone library. At flowering and bolling, soil samples from the rhizosphere of healthy cotton had the highest richness, whereas the highest evenness was found in the rhizosphere of diseased cotton at boll opening. Acidobacteria and Proteobacteria were the main phyla in the cotton rhizosphere. Other phyla, including WS3, Deinococcus-Thermus, Verrucomicrobia, Firmicutes, Bacteroidetes, Actinobacteria, Thermomicrobia, Gemmatimonadetes, Planctomycetes, Proteobacteria, Cyanobacteria and unclassified bacteria were also found in cotton rhizosphere soils. Deinococcus-Thermus and Firmicutes were only present in diseased cotton rhizospheres. PCA analysis based on the 16S rDNA clone library demonstrated that six sampling resolved three groups of assemblages.