Gou Xiaomei, Hu Yaxian, Ni Huaqian, Wang Xiang, Qiu Liping, Chang Xingchen, Shao Mingan, Wei Gehong, Wei Xiaorong
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, the Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling, Shaanxi 712100, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China; University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, the Research Center of Soil and Water Conservation and Ecological Environment, Chinese Academy of Sciences and Ministry of Education, Yangling, Shaanxi 712100, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China; College of Soil & Water Conservation Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China.
Sci Total Environ. 2024 Jan 1;906:167425. doi: 10.1016/j.scitotenv.2023.167425. Epub 2023 Sep 27.
Nutrient losses from agricultural ecosystems are increasingly threatening global environmental and human health. Although arbuscular mycorrhizal (AM) fungi have the potential to regulate soil nitrogen (N) loss by enhancing plant uptake and soil particle immobilization, the microbial mechanism behind such mycorrhizal effect is unknown. Herein, by conducting a simulated erosion experiment, we compared the effects of exogenous AM fungal inoculation (Funneliformis mosseae) on the gene abundances and enzyme activities of N-cycling processes, and associated such effect to N uptake and loss. The experiment was composed of combinations of two AM fungal treatments (control vs. AM fungal inoculation), two crops (maize vs. soybean) and two slopes of the plots (6° vs. 20°). The experimental plots subjected to natural rainfalls to simulate the erosion events. We showed that the effects of AM fungi were greater in the maize soils than in the soybean soils. In the maize soils, AM fungi increased the abundances of N-fixing (+81.1 %) and nitrifying genes (+200.7 %) and N cycling enzyme activity (+22.3 %). In the soybean soils, AM fungi increased the N-fixing gene abundance (+36.9 %) but decreased the abundance of nitrifying genes (-18.9 %). The abundance of N-fixing gene was positively correlated with N uptake but negatively correlated with N loss. Additionally, AM fungi enhanced the effects of mycorrhizal colonization and moisture but decreased the effects of nutrients on soil microbial metrics related to N-cycling processes. Therefore, AM fungal inoculation enhanced N uptake and reduced N loss by increasing N-fixing gene abundance, and that AM fungi should be preferably used for the low N environments or for the ecosystems highly limited by or competing for N.
农业生态系统中的养分流失对全球环境和人类健康构成了越来越大的威胁。尽管丛枝菌根（AM）真菌有潜力通过增强植物吸收和土壤颗粒固定来调节土壤氮（N）流失，但这种菌根效应背后的微生物机制尚不清楚。在此，通过进行模拟侵蚀实验，我们比较了外源AM真菌接种（摩西斗管囊霉）对氮循环过程中基因丰度和酶活性的影响，并将这种影响与氮吸收和流失联系起来。实验由两种AM真菌处理（对照与AM真菌接种）、两种作物（玉米与大豆）和两种坡度的地块（6°与20°）组合而成。实验地块接受自然降雨以模拟侵蚀事件。我们发现，AM真菌在玉米土壤中的效果比在大豆土壤中更显著。在玉米土壤中，AM真菌增加了固氮基因丰度（+81.1%）、硝化基因丰度（+200.7%）和氮循环酶活性（+22.3%）。在大豆土壤中，AM真菌增加了固氮基因丰度（+36.9%）但降低了硝化基因丰度（-18.9%）。固氮基因丰度与氮吸收呈正相关，但与氮流失呈负相关。此外，AM真菌增强了菌根定殖和湿度的影响，但降低了养分对与氮循环过程相关的土壤微生物指标的影响。因此，接种AM真菌通过增加固氮基因丰度增强了氮吸收并减少了氮流失，并且AM真菌应优先用于低氮环境或受氮高度限制或竞争的生态系统。
