Continental-Scale Paddy Soil Bacterial Community Structure, Function and Biotic Interaction

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background</jats:bold>: Rice paddy soil-associated microbiota participate in biogeochemical processes that underpin rice yield and soil sustainability, yet continental-scale biogeographic patterns of paddy soil microbiota remain elusive. Here, the soil bacteria of four typical Chinese rice-growing regions were characterized over large-scale space and compared with adjacent non-paddy soils.<jats:bold>Results</jats:bold>: The geographic patterns of paddy soil bacteria were significantly different from non-paddy soils, with lower alpha diversity, unique taxonomic and functional composition, and distinct co-occurrence network topology. Both stochastic and deterministic processes shaped soil bacteria assembly, but paddy exhibited a stronger deterministic signature than non-paddy samples, especially due to the roles of climate determinants. The continental biogeographic variance in bacterial community structure was driven by the competition between two mutually-exclusive bacterial modules in the co-occurrence network, and suggested antagonistic species-to-species interactions as potential selective forces may greatly shape their community structures. Keystone taxa identified in network models, such as <jats:italic>Actinobacteria</jats:italic>, <jats:italic>Chloroflexi</jats:italic>, and <jats:italic>Proteobacteria</jats:italic>, were demonstrated to be preferentially affected by environmental factors than other community members and showed high sensitivity to environmental changes, whereby the environmental factors greatly shaped the paddy soil bacterial communities by leveraging changes in keystones.<jats:bold>Conclusions</jats:bold>: The strong interplay between biotic/abiotic factors may greatly construct paddy soil microbial community and their uniqueness as compared with non-paddy soils. Microbial biogeographical analyses with novel insights into underlying determinants investigated on intensively-cultivated paddy field soils may aid in elucidating microbial changes subjected to land-use changes following the transformation between natural and agro-ecosystem, and also facilitate microbial community manipulation for better crop productivity and soil sustainability worldwide.</jats:p>