Inoculation of YH1 Leads to Reduced Metal Uptake for Grown in Mine Tailings and Metal-Polluted Soils.

Metalliferous mine tailings have a negative impact on the soil environment near mining areas and render cultivable lands infertile. Phytoremediation involving the synergism of legume and rhizobia provides a useful technique in tackling this issue with cost-effective, environmentally friendly, and easy-to-use features under adverse soil conditions. has been found to build symbiotic relationships with native rhizobia in the iron-vanadium-titanium oxide (V-Ti magnetite) mine tailing soil. Rhizobia YH1, isolated from the root nodules of , was classified as according to similarity and phylogenetic analyses of 16S rRNA, housekeeping and nitrogen fixation genes. Besides nitrogen fixation, YH1 also showed capabilities to produce indole-acetic acid (IAA) (166.77 ± 2.03 mg l) and solubilize phosphate (104.41 ± 7.48 mg l). Pot culture experiments showed that strain YH1 increased the biomass, plant height and root length of by 67.2, 39.5 and 27.2% respectively. There was also an average increase in plant N (10.0%), P (112.2%) and K (25.0%) contents compared to inoculation-free control. The inoculation of YH1 not only reduced the uptake of all metals by in the mine tailings, but also resulted in decreased uptake of Cd by up to 79.9% and Mn by up to 67.6% for plants grown in soils contaminated with Cd/Mn. It was concluded that YH1 possessed multiple beneficial effects on grown in metalliferous soils. Our findings highlight the role of YH1 in improving plant health of by reducing metal uptake by plants grown in heavy metal-polluted soils. We also suggest the idea of using - association for phytoremediation and revegetation of V-Ti mine tailings and soils polluted with Cd or Mn.