Selenium nanoparticles and glutathione synergistically enhance salt tolerance in soybean via the jasmonic acid pathway and arbutin-regulated rhizosphere microbiota

Soil salinity threatens agriculture worldwide. Nano-fertilizers offer a promising strategy to enhance tolerance to salinity and other stresses in crops, but their field performance is sometimes unpredictable, potentially due to complex interactions within the plant–microbe holobiont. Here, we designed chitosan-stabilized selenium nanoparticles (SeNPs@CS) as a novel nano-fertilizer. SeNPs@CS exhibited a uniform size (∼109.8 nm) and a positively charged surface (+14.7 mV), which confers good adhesion to plant tissues. Due to their good biocompatibility and small size, SeNPs@CS can be readily absorbed and utilized by plant leaves. When SeNPs@CS were combined with glutathione (GSH) to form a nanocomposite (SeG), they significantly promoted plant growth and enhanced salt tolerance in soybean (Glycine max). Multi-omics analyses revealed that SeG activates jasmonic acid (JA) pathways in the plant and remodels the root metabolic profile, leading to the enrichment of arbutin, a key signaling molecule, in the rhizosphere. This metabolic shift recruits and enriches beneficial salt-tolerant microbes, including Bacillus and Streptomyces, thereby establishing a protective microbiome. Treatment of plants with a synthetic microbial community (SynCom) composed of these elite strains, in combination with arbutin, reproduced the salt tolerance phenotype conferred by SeG treatment. Therefore, SeG improves salt tolerance in soybean via activation of the JA defense pathway and arbutin-driven recruitment of salt-tolerant rhizosphere microorganisms. Together, these two mechanisms enhance plant resilience under salt stress. This multi-kingdom synergistic mechanism for alleviating stress provides a new paradigm for developing smart agricultural inputs that target the plant holobiont to improve crop resilience.