期刊：New Phytologist
主题：菌根通过维持植物NO3-的吸收以应对盐胁迫
标题：Amelioration of nitrate uptake under salt stress by ectomycorrhiza with and without a Hartig net
影响因子：7.433
检测指标：NO3-流速
检测部位：杨树根（距离根尖300-400μm）
NO3-流速流实验处理方法：
小植株杨树在无/有菌株（MAJ和NAU）的情况下培养30d，之后在0或100mM NaCl处理24h/7d
NO3-流速流实验测试液成份：
NO3- measuring solution: 0.1 mM KNO3, 0.1 mM KCl, 0.1 mM CaCl2, pH 5.3 was adjusted with KOH and HCl.
H+ measuring solution: 0.1 mM NaCl, 0.1 mM MgCl2, 0.1 mM CaCl2 and 0.5 mM KCl, pH 5.3 was adjusted with KOH and HCl.
作者：北京林业大学陈少良、撒刚、邓晨
英文摘要
Salt stress is an important environmental cue impeding poplar nitrogen nutrition. Here, we characterized the impact of salinity on proton‐driven nitrate fluxes in ectomycorrhizal roots and the importance of a Hartig net for nitrate uptake.
We employed two Paxillus involutus strains for root colonization: MAJ, which forms typical ectomycorrhizal structures (mantle and Hartig net), and NAU, colonizing roots with a thin, loose hyphal sheath. Fungus‐colonized and noncolonized Populus × canescens were exposed to sodium chloride and used to measure root surface pH, nitrate (NO3−) flux and transcription of NO3− transporters (NRTs; PcNRT1.1, ‐1.2, ‐2.1), and plasmalemma proton ATPases (HAs; PcHA4, ‐8, ‐11).
Paxillus colonization enhanced root NO3− uptake, decreased surface pH, and stimulated NRTs and HA4 of the host regardless the presence or absence of a Hartig net. Under salt stress, noncolonized roots exhibited strong net NO3− efflux, whereas beneficial effects of fungal colonization on surface pH and HAs prevented NO3− loss. Inhibition of HAs abolished NO3− influx under all conditions.
We found that stimulation of HAs was crucial for the beneficial influence of ectomycorrhiza on NO3− uptake, whereas the presence of a Hartig net was not required for improved NO3− translocation. Mycorrhizas may contribute to host adaptation to salt‐affected environments by keeping up NO3− nutrition.
中文摘要（谷歌机翻）
盐胁迫是阻碍杨树氮素营养的重要环境提示。在这里，我们描述了盐度对外生菌根中质子驱动的**盐通量的影响以及Hartig网对**盐吸收的重要性。
我们采用了两种渐开线Paxillus菌株进行根定居：MAJ形成典型的外生菌根结构（地幔和Hartig网），而NAU则定植带有薄而疏松的菌丝鞘的根。将真菌定殖的和非定殖的杨×锥虫暴露于氯化钠中，用于测量根部表面的pH值，**盐（NO3-）通量和NO3-转运蛋白（NRT； PcNRT1.1，-1.2，-2.1）和质膜质子的转录。 ATPase（HAs; PcHA4，‐8，‐11）。
不论是否存在Hartig网，Paxillus菌落定植都能增强根系NO3-的吸收，降低表面pH值并刺激宿主的NRT和HA4。在盐胁迫下，未定殖的根表现出较强的净NO3-流出，而真菌定植对表面pH和HA的有益作用阻止了NO3-的流失。在所有情况下，抑制HA均消除了NO3-的涌入。
我们发现刺激HAs对于更生菌根对NO3-吸收的有益影响至关重要，而Hartig网的存在并不是改善NO3-转运所必需的。菌根可能会通过保持NO3-营养来促进宿主适应食盐环境。
结果表明：NM根尖显示中等的NO3-吸收，而真菌定殖的根则显示高7.4至11.8倍的吸收（图a）。MAJ或NAU菌根定植与NM根相比，NO3-吸收增加（图a）。此外，真菌定殖的根在盐度下保持净NO3-吸收，而NM根在短期和长期盐接触下均显示净NO3-释放。
文章链接：https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.15740