Microbial community structure in the rhizosphere of Xanthium sibiricum in the water-level-fluctuation zone of the Three Gorges Reservoir

Abstract:

Objective To understand the microbial community structure and its relationship with soil quality in the rhizosphere of the dominant plant Xanthium sibiricum in the water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir.Methods We collected the rhizosphere soil samples of X. sibiricum exposed to different flooding stress conditions in a typical WLFZ in Yunyang County, the heart of the Three Gorges Reservoir area. High-throughput sequencing was carried out to analyze the microbial diversity and community structure, and the redundancy analysis was then conducted.Results Proteobacteria was the dominant bacterial phylum in the rhizosphere bacteria of X. sibiricum under strong flooding stress (XaRLL) and weak flooding stress (XaRHL), while Ascomycota and Basidiomycota were the dominant fungal phyla in the two types of soil, respectively. Regardless of bacteria or fungi, the linear discriminant analysis effect size (LEfSe) showed that XaRLL always had more key biomarkers than XaRHL. Functional prediction revealed that PWY-3781 associated with aerobic respiration was a dominant metabolic pathway enriched by microorganisms from both XaRLL and XaRHL. Overall, the bacteria and fungi in the rhizosphere of X. sibiricum had strong responses to changes in soil physicochemical properties and enzyme activity.Conclusion The results provide a theoretical basis for understanding the relationship between plants and their rhizosphere microorganisms in the WLFZ, as well as their adaptability to strong flooding stress.