NMT历史上的今天丨Front Plant Sci：Paxillus involutus促进Cd2+吸收

NMT是基因功能的活体检测技术，已被103位诺贝尔奖得主所在单位，及北大、清华、中科院使用。

NMT历史上的今天

2017年01月06日，北京林业大学陈少良、张玉红用NMT在Frontiers in Plant Science上发表了标题为Paxillus involutus-Facilitated Cd2+Influx through Plasma Membrane Ca2+-Permeable Channels Is Stimulated by H2O2 and H+-ATPase in Ectomycorrhizal Populus × canescens under Cadmium Stress的研究成果。

期刊：Frontiers in Plant Science
主题：Paxillus involutus促进Cd2+吸收机制

标题：Paxillus involutus-Facilitated Cd2+ Influx through  Plasma Membrane Ca2+-Permeable Channels Is Stimulated  by H2O2 and H+-ATPase in Ectomycorrhizal Populus × canescens under  Cadmium Stress

影响因子：4.495

检测指标：H+、Ca2+、Cd2+、H2O2流速

作者：北京林业大学陈少良、张玉红

英文摘要

Using a Non-invasive Micro-test Technique, flux   profiles of Cd2+, Ca2+, and H+ were investigated in axenically grown   cultures of two strains of Paxillus involutus (MAJ and NAU),   ectomycorrhizae formed by these fungi with the woody   Cd2+-hyperaccumulator, Populus × canescens, and non-mycorrhizal (NM)   roots.

The influx of Cd2+ increased in fungal mycelia, NM and  ectomycorrhizal (EM) roots upon a 40-min shock, after short-term (ST, 24  h), or long-term (LT, 7 days) exposure to a hydroponic environment of  50 μM CdCl2. Cd2+ treatments (shock, ST, and LT) decreased Ca2+ influx  in NM and EM roots but led to an enhanced influx of Ca2+ in axenically  grown EM cultures of the two P. involutus isolates.

The  susceptibility of Cd2+ flux to typical Ca2+ channel blockers (LaCl3,  GdCl3, verapamil, and TEA) in fungal mycelia and poplar roots indicated  that the Cd2+ entry occurred mainly through Ca2+-permeable channels in  the plasma membrane (PM). Cd2+ treatment resulted in H2O2 production.  H2O2 exposure accelerated the entry of Cd2+ and Ca2+ in NM and EM roots.  Cd2+ further stimulated H+ pumping activity benefiting NM and EM roots  to maintain an acidic environment, which favored the entry of Cd2+  across the PM.

A scavenger of reactive oxygen species, DMTU, and  an inhibitor of PM H+-ATPase, orthovanadate, decreased Ca2+ and Cd2+  influx in NM and EM roots, suggesting that the entry of Cd2+ through  Ca2+-permeable channels is stimulated by H2O2 and H+ pumps. Compared to  NM roots, EM roots exhibited higher Cd2+-fluxes under shock, ST, and LT  Cd2+ treatments.

We conclude that ectomycorrhizal P. × canescens  roots retained a pronounced H2O2 production and a high H+-pumping  activity, which activated PM Ca2+ channels and thus facilitated a high  influx of Cd2+ under Cd2+ stress.

中文摘要（谷歌机翻）

使用非损伤微测技术，研究了两株渐渐出现的新孢子虫（MAJ和NAU）的无性培养中Cd2+，Ca2+和H+的通量分布，这是由这些真菌与木质的Cd2+-超蓄积剂，胡杨形成的外生菌根 ×canescens和非菌根（NM）根。

短期（ST，24   h）或长期（LT，7天）暴露于水培环境的40分钟休克后，真菌菌丝体，NM和根外菌根（EM）根中Cd2+的流入增加。50μM氯化镉。Cd2+处理（电击，ST和LT）减少了NM和EM根中的Ca2+流入，但导致了两个渐近线对虾分离株的无性生长EM培养物中Ca2+的流入增加。

Cd2+通量对真菌菌丝体和杨树根中典型的Ca2+通道阻滞剂（LaCl3，GdCl3，维拉帕米和TEA）的敏感性表明，Cd2+进入主要通过质膜（PM）中的Ca2+渗透通道发生。Cd2+处理导致产生H2O2。H2O2暴露加速了NM和EM根中Cd2+和Ca2+的进入。Cd2+进一步刺激了H  +的泵送活性，有利于NM和EM根系维持酸性环境，这有利于Cd2+跨PM进入。

活性氧清除剂DMTU和PM H+ -ATPase的抑制剂原钒酸盐减少了NM和EM根中Ca2+和Cd2+的内流，这表明H2O2和H+泵刺激了Cd2+通过Ca2+渗透性通道的进入。与NM根相比，EM根在电击，ST和LT Cd2+处理下表现出更高的Cd2+通量。

我们得出的结论是，外生根茎假单胞菌根保留了明显的H2O2产生和高H+泵送活性，从而激活了PM Ca2+通道，从而促进了Cd2+胁迫下Cd2+的大量涌入。

FIGURE 1 | Effects of CdCl₂ on transient kinetics of Cd²⁺, Ca²⁺, and H⁺ in Populus × canescens roots and Paxillus involutus strains MAJ and NAU. Cd²⁺ (A), Ca²⁺ (B), and H⁺ (C) kinetics were recorded before and after the required amount of 50 μM CdCl₂was introduced