Ku Yongli, Lei Yuting, Han Xiaoting, Peng Jieying, Zhu Ying, Zhao Zhong
Key Comprehensive Laboratory of Forestry, Northwest A&F University, Yangling, China.
Key Laboratory of Soil and Water Conservation and Ecological Restoration of State Forestry and Grassland Administration, Shaanxi Academy of Forestry, Xi'an, China.
Front Microbiol. 2022 Jun 24;13:918134. doi: 10.3389/fmicb.2022.918134. eCollection 2022.
Microbial-driven processes related to the nitrogen-metabolism (N-metabolism) in soil are critical for ecosystem functioning and stability. There are spatial patterns of microbial-mediated nitrogen processes, but we still lack an overview of the soil N-metabolism genes of single nitrogen-fixing tree species pure forests at a regional scale. Here, we investigated the spatial variation and drivers of microbial N-metabolism genes in the rhizosphere soil of on the Loess Plateau by metagenomic technology. We found that the distance-decay of soil N functional gene similarities in forests on the Loess Plateau spanning a geographic distance of 230 km was significant ( < 0.001). The gene composition and co-occurrence patterns in the process of soil microbial N-metabolism were very different, and they were mainly driven by soil pH and MAP (mean annual precipitation). The proportion of positive links and edges co-occurrence networks between N functional genes increased with increasing pH, suggesting that increasing pH promoted connections between functional genes. The relative frequencies of N-metabolism pathways were consistent on the Loess Plateau, the abundance of ammonia assimilation pathway was highest, and the abundance of the nitrogen fixation pathway was the lowest; only the abundance of the nitrogen fixation pathway was not significantly different. The bacterial and archaeal communities involved in soil nitrogen metabolism were significantly different. Structural equation modeling showed that decreases in soil pH and MAP mainly affected the increase in nitrogen functional gene abundance through an increase in the diversity of N-metabolism microorganisms. In conclusion, this study provides a baseline for biogeographic studies of soil microbe functional genes.
与土壤中氮代谢（N-代谢）相关的微生物驱动过程对生态系统功能和稳定性至关重要。微生物介导的氮过程存在空间格局，但在区域尺度上，我们仍缺乏对单一固氮树种纯林土壤N-代谢基因的全面了解。在此，我们通过宏基因组技术研究了黄土高原[具体树种缺失]根际土壤中微生物N-代谢基因的空间变异及其驱动因素。我们发现，黄土高原上地理距离跨度达230公里的[具体树种缺失]森林中，土壤N功能基因相似性的距离衰减显著（<0.001）。土壤微生物N-代谢过程中的基因组成和共现模式差异很大，主要受土壤pH值和年均降水量（MAP）驱动。N功能基因之间正连接和边共现网络的比例随pH值升高而增加，表明pH值升高促进了功能基因之间的联系。黄土高原上N-代谢途径的相对频率一致，氨同化途径的丰度最高，固氮途径的丰度最低；只有固氮途径的丰度差异不显著。参与土壤氮代谢的细菌和古菌群落显著不同。结构方程模型表明，土壤pH值和MAP的降低主要通过增加N-代谢微生物的多样性来影响氮功能基因丰度的增加。总之，本研究为土壤微生物功能基因的生物地理学研究提供了基线。
