Structure and function of bacterial community in soil-root continuum of Camellia oleifera

The microbial community in the rhizosphere is crucial for promoting plant growth and maintaining plant health. Due to natural factors and inappropriate human management, the sustainable production of Camellia oleifera is severely limited. Currently, there is a lack of research on the structure, composition and function of bacterial communities in the soil-root continuum (bulk soil, rhizosphere soil, and root endosphere) of C. oleifera . To better understand the soil-root-microbe interactions of C. oleifera , we used Illumina HiSeq to investigate the species composition, diversity, community assembly, and potential functions of root-associated bacterial communities in C. oleifera . The analysis shown that there were significant differences in the composition and structure of bacterial communities in different ecological niches. Proteobacteria ( 1174 - 901 - 12 ), Actinobacteria ( Acidothermus ), and Firmicutes were significantly enriched in the root endosphere (RE), while Acidobacteria , Chloroflexi , and Verrucomicrobia ( Candidatus_Xiphinematobacter ) were significantly enriched in the bulk soil (S) and rhizosphere (RS). PCoA analysis revealed significant differences in bacterial community structure between different ecological niches of C. oleifera soil-root continuum (RS vs. S: P = 0.05; RE vs. S: P = 0.04; RE vs. RS: P = 0.005). The deterministic process (relative contributions: S = 50.0%, RS = 64.7%, and RE = 75.5%) dominated the community assembly in the C. oleifera roots. The ecological niche effected the complexity and stability of C. oleifera soil-root continuum bacterial community, and the co-occurrence network of RE was more complex than RS and S. A number of genera such as Novosphingobium , Bdellovibrio , Haemophilus , and Roseiarcus have been identified as hub microbial taxa. These hub taxa have important potential functions in degrading polycyclic aromatic hydrocarbon pollution, promoting nutrient transformation, and enhancing plant stress resistance. Finally, the functional prediction results of FAPROTAX shown significant differences in the functional categories of bacterial communities in different ecological niches ( P = 0.001), with chemotrophic heterotrophic dominant. This study elucidated the composition, structure, assembly mechanism, hub groups, and community functions of bacterial communities in different ecological niches of C. oleifera soil-root continuum, providing a theoretical basis for the future exploration of microbial functions and the study of biological fertilizers.