The effects of arbuscular mycorrhizal fungi on sex-specific responses to Pb pollution in Populus cathayana

• Sex-specific responses in Populus cathayana to a diffused level of Pb pollution were investigated, and without obvious inhibition in growth in both sexes was found.
• Symbiosis with exotic Funneliformis mosseae did not significantly affect growth and biomass allocation of both sexes, but improved the status of P nutrient.
• Inoculation with F. mosseae increased the activity of antioxidant enzymes of P. cathayana, and thus mitigated oxidation stress induced by Pb.
• Exotic F. mosseae could promote the uptake and accumulation of Pb in roots of females, but not in those of males.

Using fast-growing trees to remediate soils polluted by heavy metals (HMs) has received increasingly more attention, especially for recalcitrant Pb, as one of the most seriously toxic HMs. However, little is known about the responses of plants to a diffused level of Pb pollution, and a more combined phytoremediation technique is needed to explore. In this study, an arbuscular mycorrhizal fungus (AMF), i.e., Funneliformis mosseae, isolated from Populus euphratica distributed in a tailing of Pb/Zn ore, was introduced to investigate its effects on sex-specific responses of P. cathayana in morphology, physiology, and Pb phytoremediation capacity, when exposed to a diffused level of Pb pollution (100 mg Pb2+ kg−1 dry soil). Symbiosis with exotic AMF did not significantly affect growth of both sexes and biomass allocation. However, when inoculated with AMF, both sexes absorbed more P, but not N in the roots, especially when exposed to the exogenous addition of Pb. The improvement of nutrient status under such conditions might be associated with a further increase in activity of antioxidant enzymes (particularly for superoxide dismutase (SOD) and catalase (CAT)), and the mitigation of oxidation stress induced by excessive reactive oxygen species (ROS). We also observed that exotic AMF could promote the uptake and accumulation of Pb in roots of females, but not in that of males. Therefore, under this diffused pollution level, the infected females might be more suitable for remediation of this metal than infected males, due to the higher capacity of HM accumulation without obvious negative effects on growth and physiological traits. Moreover, field surveys are needed to testify our experimental results, due to diversity of soil microbial community and complexities of their interaction.