土壤-根连续体的微生物在生态系统功能中起着关键作用。黄土高原以其严重的土壤侵蚀和厚厚的黄土而闻名于世,从东南到西北,平均年降水量(MAP)和土壤养分减少。然而,环境因素对四个微生境(块状土壤,根际,根际平面,和内圈)在黄土高原沿环境梯度的土壤-根连续体中仍不清楚。在这项研究中,我们调查了黄土高原从温带到沙漠草原的82个野外地点,中国,为了评估细菌的多样性,composition,社区集会,使用细菌16S重组DNA扩增子测序,沿着环境梯度在土壤-根连续体中同时出现网络。我们发现,微生境解释了该地区细菌多样性和群落组成变化的最大来源。环境因素(例如,MAP,土壤有机碳,和pH值)影响了土壤,根际,和根际平面细菌群落,但是它们对细菌群落的影响随着从土壤到根际平面与根的距离增加而降低,MAP扩大了根际和根际平面与块状土壤的微生物群落差异。此外,随机组装过程驱动了内圈群落,而土壤,根际,根际平面群落主要受确定性过程的变量选择控制,这表明从温带草原到沙漠草原的重要性日益增加。此外,根际平面群落中微生物网络的特性表明沙漠草原中的网络更加稳定,可能赋予微生物群落在较高胁迫环境中的抗性。总的来说,我们的结果表明,土壤-根连续体中的细菌群落在环境梯度上具有不同的敏感性和组装机制。这些模式是由黄土高原与根的邻近度和环境胁迫变化交织在一起的同时形成的。
Microorganisms of the soil-root continuum play key roles in ecosystem function. The Loess Plateau is well known for its severe soil erosion and thick loess worldwide, where mean annual precipitation (MAP) and soil nutrients decrease from the southeast to the northwest. However, the relative influence of environmental factors on the microbial community in four microhabitats (bulk soil, rhizosphere, rhizoplane, and endosphere) in the soil-root continuum along the environmental gradient in the Loess Plateau remains unclear. In this study, we investigated 82 field sites from warm-temperate to desert grasslands across the Loess Plateau,
China, to assess the bacterial diversity, composition, community assembly, and co-occurrence networks in the soil-root continuum along an environmental gradient using bacterial 16S recombinant DNA amplicon sequencing. We discovered that the microhabitats explained the largest source of variations in the bacterial diversity and community composition in this region. Environmental factors (e.g., MAP, soil organic carbon, and pH) impacted the soil, rhizosphere, and rhizoplane bacterial communities, but their effects on the bacterial community decreased with increased proximity to roots from the soil to the rhizoplane, and the MAP enlarged the dissimilarity of microbial communities from the rhizosphere and rhizoplane to bulk soil. Additionally, stochastic assembly processes drove the endosphere communities, whereas the soil, rhizosphere, and rhizoplane communities were governed primarily by the variable selection of deterministic processes, which showed increased importance from warm-temperate to desert grasslands. Moreover, the properties of the microbial networks in the rhizoplane community indicate more stable networks in desert grasslands, likely conferring the resistance of microbial communities in higher stress environments. Collectively, our results showed that the bacterial communities in the soil-root continuum had different sensitivities and assembly mechanisms along an environmental gradient. These patterns are shaped simultaneously by the intertwined dimensions of proximity to roots and environmental stress change in the Loess Plateau.