Microbes with high–abundance attributes dominate the prokaryote communities of saline–alkali soil and construct more complex networks in the plant rhizosphere

Understanding the interactions between plants and microbes in terms of core and/or keystone taxa is of great importance for promoting salt tolerant of plants and comprehensive utilisation of saline–alkali lands. However, our knowledge about the dominant microbial categories and their response to plant growth is limited. Here, we distinguished the categories of core and keystone taxa by classifying the prokaryotic categories and conducting network analysis in saline–alkali lands. Moreover, we explored how these important taxa varied between the plant rhizosphere and bulk soils. Overall, six categories of prokaryotes were identified. Approximately one–tenth of the species with high–abundance attributes accounted for two–thirds of total prokaryotes. Moreover, network analysis showed that nearly all links among the nodes were positive; and the identified keystone taxa mainly belonged to categories with high–abundance attributes. Furthermore, in the rhizosphere, a decreasing trend in the correlations of microbial diversity indices and community compositions with the soil properties was observed compared with those in the bulk soil. However, more keystone taxa and complex modules were strongly correlated with changes in the soil properties. These results suggest that the plant rhizosphere can recruit keystone prokaryotes with high–abundance attributes by establishing a syntrophic association between the plant and keystone taxa, which subsequently construct a complex microbial network structure. Although the ecological functions of the targeted keystone taxa need to be confirmed, our findings provide a potential method for constructing a core artificial microbiome with multiple approaches, further helping to develop microbial strategies to ameliorate salt stress in plants in saline–alkali lands.