Bacterial communities and dynamics in the rhizosphere of maize

Rhizosphere microbiota have significant contributions to crop health, productivity and carbon sequestration. As an important economic crop, rhizosphere microbial communities of maize (Zea mays) have been intensively investigated using various approaches. However, low-resolution profiling methods often make it difficult to understand the complicated rhizosphere microbial communities and their dynamics. In this study, maize rhizosphere bacterial communities were analyzed using the pyrosequencing method, which revealed a core assembly of bacteria enriched in the rhizosphere. We showed that the rhizosphere of maize is preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by one or two dominating classes or families or genera. Genera Massilia, Burkholderia, Ralstonia, Dyella, Chitinophaga and Sphingobium were enriched and dominated in maize rhizosphere. Rhizosphere bacterial communities dramatically changed through different growth stages at family, genus and OTU levels. Genera Massilia, Flavobacterium, Arenimonas and Ohtaekwangia were relatively abundant at early stages of root development, while genera Burkholderia, Ralstonia, Dyella, Chitinophaga, Sphingobium, Bradyrhizobium and Variovorax population were dominant at later developmental stages. Comparison of pyrosequencing data collected in Illinois, USA in this study with the available data from Germany indicated distinctive patterns of rhizosphere microbiome of maize, implying that some site-specific factors, such as soil properties, may also play important roles in shaping the structure of rhizosphere bacterial community.