Plant species shape the structure and function of rhizobacterial communities in arid grasslands

Abstract

Rhizosphere microorganisms play a key role in sustaining plant health, mediating nutrient cycling, and maintaining soil structural integrity within grassland ecosystems. However, the response patterns of rhizosphere microbial communities in grassland ecosystems, as well as their complex interactions with plant communities and ecosystem multifunctionality, remain to be elucidated. To further investigate the response mechanisms of rhizosphere microbial communities across different plant species, 16S rRNA high-throughput sequencing technology was employed to analyze bacterial diversity and community structures in rhizosphere soils of different plant species (Taraxacum mongolicum, Poa annua, and Daucus carota) within the arid grassland region of Xinjiang, China. Subsequently, the Tax4Fun software package was used to elucidate potential metabolic pathways and ecological functions. The results demonstrated that the number of ASVs in the rhizosphere soils was ranked in the order of P. annua, D. carota, and T. mongolicum. However, no statistically significant differences were observed in the bacterial α-diversity among these plant species. The predominant genera across all samples were Sphingomonas, Haliangium, and Nocardioides. Additionally, P. annua exhibited unique dominant genera that included Pseudomonas and Stenotrophomonas. Principal coordinates analysis (PCoA) based on weighted UniFrac dissimilarity, in combination with a separate analysis of similarities (ANOSIM), revealed significant differences in bacterial communities among plant species. The co-occurrence network analysis revealed interactions among rhizospheric bacterial communities in plants. The rhizosphere microbiome exhibited predominantly positive correlations with a smaller proportion of negative correlations, potentially indicating microbial interactions as adaptations to harsh environmental conditions. The findings provide a theoretical basis for advancing the understanding of different plant environmental adaptation strategies and the ecological restoration of arid steppe ecosystems.

Keywords: Arid grassland; Bacterial community structure; Ecological restoration; Plant species; Rhizosphere soils.