María Lourdes Gil-Cardeza, Stéphane Declerck, Maryline Calonne-Salmon
Instituto de Investigaciones en Cs. Agrarias de Rosario (IICAR, CONICET-UNR), Facultad de Cs Agrarias, Universidad Nacional de Rosario, Campo Exp. Villarino, Zavalla, 2123, Argentina.
Université Catholique de Louvain, Earth and Life Institute, Mycology, Croix du Sud, 2 box L7.05.06, B-1348 Louvain-la-Neuve, Belgium.
Heliyon. 2021 Jan 5;7(1):e05891. doi: 10.1016/j.heliyon.2020.e05891. eCollection 2021 Jan.
Arbuscular mycorhizal fungi (AMF) associated to plants may represent a promising phyto-remediation avenue due to the widely documented role of these fungi in alleviation of numerous abiotic (e.g. heavy metals) stresses. In the present work, it was the objective to study the dynamics of inorganic phosphorus (Pi) and chromium(VI) (Cr(VI)) and total Cr uptake by the plant-AMF associates + MUCL 41833, under increasing (i.e. 0, 0.1, 1 and 10 mg L) concentrations of Cr(VI). The plant-AMF associates were grown in a circulatory semi-hydroponic cultivation system under greenhouse conditions. We demonstrated that Cr(VI) had an hormesis effect on root colonization of maize. Indeed, at 0.1 and 1 mg L Cr(VI), root colonization was increased by approximately 55% as compared to the control (i.e. in absence of Cr(VI) in the solution), while no difference was noticed at 10 mg L Cr(VI) (P ≤ 0.05). However, this did not result in an increased uptake of Pi by the AMF-colonized plants in presence of 0.1 mg L Cr(VI) as compared to the AMF control in absence of Cr(VI) (P ≤ 0.05). Conversely, the presence of 1 mg L Cr(VI) stimulated the Pi uptake by non-mycorrhizal plants, which absorbed 17% more Pi than their mycorrhizal counterparts (P ≤ 0.05). In addition, the non-mycorrhizal plants absorbed, in average, 8% more Cr(VI) than the mycorrhizal plants. Overall, our results prompt the hypothesis that in presence of AMF, the regulation of uptake of Cr(VI) and Pi by plant roots is done mostly by the fungus rather than the root cells. This regulated uptake of roots associated to AMF would indicate that the symbiosis could benefit the plants by providing a stable Pi uptake in a Cr(VI) polluted environment.
与植物相关的丛枝菌根真菌（AMF）可能是一种很有前景的植物修复途径，因为这些真菌在缓解多种非生物胁迫（如重金属胁迫）方面的作用已被广泛记载。在本研究中，目的是研究在六价铬（Cr(VI)）浓度增加（即0、0.1、1和10 mg/L）的情况下，植物-AMF共生体+MUCL 41833对无机磷（Pi）、六价铬（Cr(VI)）和总铬的吸收动态。植物-AMF共生体在温室条件下的循环半水培栽培系统中生长。我们证明，Cr(VI)对玉米的根定殖有刺激作用。事实上，在0.1和1 mg/L Cr(VI)浓度下，与对照（即溶液中不存在Cr(VI)）相比，根定殖增加了约55%，而在10 mg/L Cr(VI)浓度下未观察到差异（P≤0.05）。然而，与不存在Cr(VI)的AMF对照相比，在0.1 mg/L Cr(VI)存在的情况下，AMF定殖的植物对Pi的吸收并未增加（P≤0.0）。相反，1 mg/L Cr(VI)的存在刺激了非菌根植物对Pi的吸收，非菌根植物比菌根植物多吸收17%的Pi（P≤0.05）。此外，非菌根植物平均比菌根植物多吸收8%的Cr(VI)。总体而言，我们的结果提示了这样一个假设：在存在AMF的情况下，植物根系对Cr(VI)和Pi的吸收调节主要由真菌而非根细胞完成。与AMF相关的根系这种受调节吸收表明，这种共生关系可以通过在Cr(VI)污染环境中提供稳定的Pi吸收而使植物受益。
