NEW PHYTOL ：北京林业大学丨菌根通过维持植物NO3-的吸收以应对盐胁迫（附NMT实验体系）
- 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
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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硝酸盐通量的影响以及Hartig网对硝酸盐吸收的重要性。
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，硝酸盐（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：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
