Ectomycorrhizal Fungal Strains Facilitate Cd<sup>2+</sup> Enrichment in a Woody Hyperaccumulator under Co-Existing Stress of Cadmium and Salt
Cadmium (Cd<sup>2+</sup>) pollution occurring in salt-affected soils has become an increasing environmental concern in the world. Fast-growing poplars have been widely utilized for phytoremediation of soil contaminating heavy metals (HMs). However, the woody Cd<sup>2+</sup>-h...
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| Autores principales: | , , , , , , , , , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/a0dfe0adf85347f9a2c21350ed2cdf64 |
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| Sumario: | Cadmium (Cd<sup>2+</sup>) pollution occurring in salt-affected soils has become an increasing environmental concern in the world. Fast-growing poplars have been widely utilized for phytoremediation of soil contaminating heavy metals (HMs). However, the woody Cd<sup>2+</sup>-hyperaccumulator, <i>Populus</i> × <i>canescens</i>, is relatively salt-sensitive and therefore cannot be directly used to remediate HMs from salt-affected soils. The aim of the present study was to testify whether colonization of <i>P.</i> × <i>canescens</i> with ectomycorrhizal (EM) fungi, a strategy known to enhance salt tolerance, provides an opportunity for affordable remediation of Cd<sup>2+</sup>-polluted saline soils. Ectomycorrhization with <i>Paxillus involutus</i> strains facilitated Cd<sup>2+</sup> enrichment in <i>P.</i> × <i>canescens</i> upon CdCl<sub>2</sub> exposures (50 μM, 30 min to 24 h). The fungus-stimulated Cd<sup>2+</sup> in roots was significantly restricted by inhibitors of plasmalemma H<sup>+</sup>-ATPases and Ca<sup>2+</sup>-permeable channels (CaPCs), but stimulated by an activator of plasmalemma H<sup>+</sup>-ATPases. NaCl (100 mM) lowered the transient and steady-state Cd<sup>2+</sup> influx in roots and fungal mycelia. Noteworthy, <i>P. involutus</i> colonization partly reverted the salt suppression of Cd<sup>2+</sup> uptake in poplar roots. EM fungus colonization upregulated transcription of plasmalemma H<sup>+</sup>-ATPases (<i>PcHA4</i>, <i>8</i>, <i>11</i>) and annexins (<i>Pc</i><i>ANN1</i>, <i>2</i>, <i>4</i>), which might mediate Cd<sup>2+</sup> conductance through CaPCs. EM roots retained relatively highly expressed <i>PcHAs</i> and <i>PcANNs</i>, thus facilitating Cd<sup>2+</sup> enrichment under co-occurring stress of cadmium and salinity. We conclude that ectomycorrhization of woody hyperaccumulator species such as poplar could improve phytoremediation of Cd<sup>2+</sup> in salt-affected areas. |
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