Molybdenum Nanofertilizer Boosts Biological Nitrogen Fixation and Yield of Soybean through Delaying Nodule Senescence and Nutrition Enhancement

Soybean (Glycine max) is a crop of globalsignificanceand has low reliance on N fertilizers due to its biological nitrogenfixation (BNF) capacity, which harvests ambient N-2 as acritical ecosystem service. BNF can be severely compromised by abioticstresses. Enhancing BNF is increasingly important not only to alleviateglobal food insecurity but also to reduce the environmental impactof agriculture by decreasing chemical fertilizer inputs. However,this has proven challenging using current genetic modification orbacterial nodulation methods. Here, we demonstrate that a single applicationof a low dose (10 mg/kg) of molybdenum disulfide nanoparticles (MoS2 NPs) can enhance soybean BNF and grain yield by 30%, comparedwith conventional molybdate fertilizer. Unlike molybdate, MoS2 NPs can more sustainably release Mo, which then is effectivelyincorporated as a cofactor for the synthesis of nitrogenase and molybdenum-basedenzymes that subsequently enhance BNF. Sulfur is also released sustainablyand incorporated into biomolecule synthesis, particularly in thiol-containingantioxidants. The superior antioxidant enzyme activity of MoS2 NPs, together with the thiol compounds, protect the nodulesfrom reactive oxygen species (ROS) damage, delay nodule aging, andmaintain the BNF function for a longer term. The multifunctional natureof MoS2 NPs makes them a highly effective strategy to enhanceplant tolerance to abiotic stresses. Given that the physicochemicalproperties of nanomaterials can be readily modulated, material performance(e.g., ROS capturing capacity) can be further enhanced by severalsynthesis strategies. This study thus demonstrates that nanotechnologycan be an efficient and sustainable approach to enhancing BNF andcrop yield under abiotic stress and combating global food insecurity.