Pulling nutrients from Mo-polluted soil by arbuscular mycorrhizal fungi extraradical mycelia is quenching thirsty with poison.

Abstract

As an extension of plant root system, arbuscular mycorrhizal fungi (AMF) extraradical mycelium (ERM) can break the limitation of rhizosphere and play an important role in plant nutrient acquisition. However, it remains unclear whether ERM is smart enough to pick out nutrients while avoiding poison, or is unable to pick out nutrients and have to absorb poisons together. Therefore, the present study employed a compartment device to separate the mycelia from roots, aiming to explore the nutrient absorption pathways of mycelia in molybdenum (Mo) pollution soil after inoculation with AMF in maize and vetch plants. The results showed that mycelia increased the absorption of nutrients in maize and vetch plants, while reducing the biomass of the plants. In addition, mycelia increased the Mo concentration of plants. The highest contribution of mycelia to Mo concentration in plants reached 114.06%. For different plants, maize tends to immobilize Mo in roots, while vetch tend to transport Mo to shoots under Mo stress. Additionally, variance partitioning analysis proved that the contribution of nutrients to biomass was the largest, with the interpretation rates reaching 65.09% and 47.26% in maize and vetch plants, respectively. The decrease in plant biomass was due to the toxic effects of Mo. Furthermore, the negative effect of the interaction of Mo, mycelia and nutrients on biomass further proved that the nutrients absorption of mycelia under Mo-polluted soil may be carried out in the way of quenching thirsty with poison.