Metabolite profiling indicates comparative effects of magnesium oxide nanoparticle vs. its bulk priming on lead tolerance and nutritional quality in mungbean sprouts.

Lead (Pb) toxicity threatens the nutritional quality of edible sprouts. Whether MgO nanoparticles (MgO-NP) outperform bulk MgO in protecting mungbean sprouts against Pb toxicity remains unclear. Pb stress reduced seed germination, and sprout growth. A dose-response experiment showed that increasing MgO-bulk up to 600 mg L-1 did not reproduce the MgO-NP response, with higher bulk concentrations proving phytotoxic. MgO-NP priming at 100 mg L-1 improved germination (93% vs. 87% with MgO-bulk) and reduced total Pb accumulation (62.5% vs. 36.4%) and bioaccessible Pb by 76.3% while maintaining higher Mg bioavailability (21% vs. 18% with MgO bulk) in edible tissues. MgO-NP priming further enhanced T-AOC (138% vs. 104%), DPPH scavenging activity (61% vs. 50%), total flavonoids (102% vs. 85%), and total phenolics (63% vs. 51%) relative to Pb stress, associated with enrichment of phenylpropanoid and flavonoid pathways. These findings demonstrate that MgO-NP outperforms MgO-bulk in mitigating Pb toxicity while improving nutritional quality.