NMT历史上的今天丨Front Plant Sci：Paxillus involutus促进Cd2+吸收机制
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
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.
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。
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 CdCl2 was introduced into the measuring chamber.