A transregional study of rhizosphere microbial community structure and diversity in desert plants

Both plant traits, soil properties and climate are pivotal factors affecting microbial communities. However, there is still limited information about their importance in rhizosphere soil communities, particularly in less-studied shrub ecosystems. Here, we focused on 13 different geographic populations of the desert plant Caragana stenophylla, to investigate the diversity and composition of rhizosphere soil bacterial and fungal communities, as well as the factors shaping rhizosphere soil microbial communities. It was found that the different geographic populations of rhizosphere soil microbial diversity differed significantly. Piecewise SEM analysis result indicates that the balance of positive and negative effects of plant traits, climate, and soil characteristics collectively determines their impact on the diversity of rhizosphere soil microorganisms. The co-occurrence network indicated that bacterial communities accounting for 57.48% and fungal communities accounting for 42.52% of rhizosphere soil microbial. Results showed that the bacterial communities were dominated by Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidota, Planctomycetota, Acidobacteriota, which accounted for 85.38-96.34% of all bacterial sequences, and the relative abundance of eight phyla showed significant changes between different geographical populations. The fungal communities were Ascomycota and Basidiomycota which accounted for 68.62-98.08% of all bacterial sequences, and the relative abundance of Ascomycota showed significant changes between different geographical populations. Permutational multivariate analysis of variance and redundancy analysis manifest that the variations of rhizosphere bacterial communities mostly explained by soil properties (AP, EC, TK, TN) and plant traits (SLA, RP, SRL, H), whereas the explaining of fungal communities only depend on soil characteristics (EC, AN). Our results not only reveal the significant impact of plant traits and soil fertility on microbial communities but also underscore the crucial role of environmental factors in maintaining microbial diversity. Overall, this study enhances our understanding of the relationship between the structure and diversity of microbial communities in the rhizosphere of Caragana stenophylla and plant traits as well as abiotic factors. It provides a scientific basis for investigating the ecological adaptation mechanisms of desert plants. Furthermore, these findings will contribute to future applications and practices in desert ecological restoration and plant selection, promoting the sustainable development of desert ecosystems.