Soil properties affect bacterial community assembly and co-occurrence network in tobacco rhizosphere

Abstract:

[ Objective] To understand the contribution of microbial community assembly in plant rhizosphere to the stability of farmland ecosystem. [ Method s] High-throughput sequencing and bioinformatics tools were employed to explore the relationship between the bacterial community in tobacco rhizosphere and soil properties in the eight major tobacco-planting ecotopes in China. [ Result s] The most abundant bacterial classes were Actinobacteria, Alphaproteobacteria, Gammaproteobacteria, and Thermoleophilia. The composition of bacterial community presented a clustering pattern according to ecotopes, and the similarity of bacterial community among samples had a significantly negative correlation with spatial distance. The co-occurrence network of bacterial interactions indicated a higher proportion of positive links than that of negative links between bacteria. The network of Wuling-Qinba mountains (WQM), Huanghuai plain (HHP), Nanling hills (NLH), and Yimeng hills (YMH) presented high modularity. Micromonospora as the network hub in NLH and HHP contributed to the stability of microbial network. Bryobacter and Arenimonas were identified as module hubs in NLH and their characteristics rather than relative abundance determined their role in stabilizing bacterial co-occurrence network. The results of redundancy analysis showed that pH, available iron (availFe), exchangeable magnesium (exchMg), and available manganese (availMn) remarkably affected the bacterial community assembly in tobacco rhizosphere. [ Conclusion ] The homogenization and habitat specificity of bacterial community assembly in tobacco rhizosphere were affected by soil pH, availFe, exchMg, and availMn. Micromonospora, Bryobacter, and Arenimonas played an important role in the bacterial community of tobacco rhizosphere.

Key words:bacterial community assembly;co-occurrence network;tobacco;rhizosphere;habitat specificity