Abstract
Understanding interspecies interactions is essential to predict the response of microbial communities to exogenous perturbation. Herein, rhizospheric and bulk soils were collected from five developmental stages of soybean, which grew in soils receiving 16-year nitrogen inputs. Bacterial communities and functional profiles were examined using high-throughput sequencing and quantitative PCR, respectively. The objective of this study was to identify the key bacterial interactions that influenced community dynamics and functions. We found that the stages of soybean development outcompeted nitrogen fertilization management in shaping bacterial community structure, while fertilization treatments significantly shaped the abundance distribution of nitrogen functional genes. Temporal variations in bacterial abundances increased in bulk soils, especially at the stage of soybean branching, which helps to infer underlying negative interspecies interactions. Members of Cyanobacteria and Actinobacteria actively engaged in inter-phylum negative interactions in bulk soils and soybean rhizosphere, respectively. Furthermore, the negative interactions between nitrogen-fixing functional groups and the reduction of nifH gene abundance were coupled during soybean development, which may help to explain the linkages between population dynamics and functions. Overall, these findings highlight the importance of inter-phylum negative interactions in shaping the correlation patterns of bacterial communities and in determining soil functional potential.
Highlights
The soil microbiome plays an integral role in nutrient cycling and constitutes an important resource for sustainable agricultural production (van der Heijden et al 2008)
Spatiotemporal variations of bacterial community and nitrogen functional genes Bacterial community differences were mainly driven by stage, and secondarily, by fertilization treatment
Temporal variations of bacterial community shaped by rhizosphere effect Root exudates can shape soil microbial communities during plant development (Chen et al 2019)
Summary
The soil microbiome plays an integral role in nutrient cycling and constitutes an important resource for sustainable agricultural production (van der Heijden et al 2008). Soybean cultivation as green manure offers a promising approach to ameliorate the negative impact on soil nutrients caused by the longterm application of chemical nitrogen fertilizer. Exploring how soil bacterial communities and nitrogen functional traits respond to soybean cultivation after longterm nitrogen fertilization could help to guide agricultural management. Both exogenous and endogenous factors shape microbial communities and their functions (Konopka et al 2015; Zhang et al 2021). Agricultural management and plant selection interactively affect soil microbial communities and nitrogen cycling (Schmidt et al 2019). The effects of plant and environmental factors on microbial communities have been well studied (Brown et al 2020; Mendes et al 2014), the consequences of bacterial interactions for communities and functions have not been fully understood
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