三峡水库消落区苍耳根际微生物群落结构解析

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

摘要:

目的 揭示三峡水库消落区典型优势植物苍耳(Xanthium sibiricum)根际微生物群落结构特征，阐明其与土壤质量的关系。方法 在三峡库区腹心所在地云阳县典型消落区采集不同水淹胁迫强度下的苍耳根际土壤，随后进行高通量测序、微生物多样性分析、群落结构解析和冗余分析。结果 在水淹胁迫强(XaRLL)和低(XaRHL)区域中，变形菌门(Proteobacteria)是苍耳根际细菌群落中共同的最优势细菌门，最优势的真菌门则分别为子囊菌门(Ascomycota)和担子菌门(Basidiomycota)。无论是细菌还是真菌，线性判别分析(linear discriminant analysis effect size, LEfSe)结果显示，XaRLL的关键生物标志物总是多于XaRHL。功能预测分析发现，与有氧呼吸相关的PWY-3781是XaRLL和XaRHL二者共同富集的优势代谢途径。整体而言，苍耳根际微生物群落对土壤的理化性质和酶活的变化反应强烈。结论 本研究为理解水库消落区植物与其根际微生物的关系，以及它们对强烈水淹胁迫逆境的适应性提供了理论基础。

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.