Wu Fei, Fang Fengru, Wu Na, Li Li, Tang Ming
State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Laboratory of Lingnan Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China.
College of Forestry, Northwest A&F University, Yangling, China.
Front Microbiol. 2020 Feb 28;11:176. doi: 10.3389/fmicb.2020.00176. eCollection 2020.
Plants and other organisms in the ecosystem compete for the limited nitrogen (N) in the soil. Formation of a symbiotic relationship with arbuscular mycorrhizal fungi (AMF) may influence plant competitiveness for N. However, the effects of AMF on plant nitrate (NO ) uptake capacity remain unknown. In this study, a pot experiment was conducted to investigate the effects of N application and inoculation on the root absorbing area, uptake kinetics of NO , and the expression of NO transporter () genes in × 'Neva'. The results showed that . colonized more than 70% of the roots of the poplar and increased root active absorbing area/total absorbing area. The uptake kinetics of NO by poplar fitted the Michaelis-Menten equation. Mycorrhizal plants had a higher maximum uptake rate ( ) value than non-mycorrhizal plants, indicating that . enhanced the NO uptake capacity of poplar. The expression of in roots, namely, , , , , , and , was decreased by . under conditions of 0 and 1 mM NHNO. This study demonstrated that the improved NO uptake capacity by . was not achieved by up-regulating the expression of in roots. The mycorrhizal pathway might repress root direct pathway in the NO uptake by mycorrhizal plants.
生态系统中的植物和其他生物会争夺土壤中有限的氮（N）。与丛枝菌根真菌（AMF）形成共生关系可能会影响植物对氮的竞争力。然而，AMF对植物硝酸盐（NO₃⁻）吸收能力的影响仍不清楚。在本研究中，进行了盆栽试验，以研究施氮和接种对בNeva’杨树根系吸收面积、NO₃⁻吸收动力学以及NO₃⁻转运蛋白（NRT）基因表达的影响。结果表明，AMF定殖在70%以上的杨树根系上，并增加了根系活跃吸收面积/总吸收面积。杨树对NO₃⁻的吸收动力学符合米氏方程。菌根植物的最大吸收速率（Vmax）值高于非菌根植物，表明AMF增强了杨树对NO₃⁻的吸收能力。在0和1 mM NH₄NO₃条件下，AMF降低了根系中NRT1.1、NRT1.2、NRT2.1、NRT2.2、NRT2.3和NAR2.1的表达。本研究表明，AMF提高杨树对NO₃⁻的吸收能力并不是通过上调根系中NRT基因的表达来实现的。菌根途径可能会抑制菌根植物在NO₃⁻吸收中的根系直接途径。
