Engineering Climate-Resilient Rice Using a Nanobiostimulant-Based "Stress Training" Strategy

Under a changing climate, cultivating climate-resilientcrops willbe critical to maintaining food security. Here, we propose the applicationof reactive oxygen species (ROS)-generating nanoparticles as nanobiostimulantsto trigger stress/immune responses and subsequently increase the stressresilience of plants. We established three regimens of silver nanoparticles(AgNPs)-based "stress training": seed training (ST),leaf training (LT), and combined seed and leaf training (SLT). Trainedrice seedlings were then exposed to either rice blast fungus (Magnaporthe oryzae) or chilling stress (10 degrees C). Theresults show that all "stress training" regimes, particularlySLT, significantly enhanced the resistance of rice against the fungalpathogen (lesion size reduced by 82% relative to untrained control).SLT also significantly enhanced rice tolerance to cold stress. Themechanisms for the enhanced resilience were investigated with metabolomicsand transcriptomics, which show that "stress training"induced considerable metabolic and transcriptional reprogramming inrice leaves. AgNPs boosted ROS-activated stress signaling pathwaysby oxidative post-translational modifications of stress-related kinases,hormones, and transcriptional factors (TFs). These signaling pathwayssubsequently modulated the expression of defense genes, includingspecialized metabolites (SMs) biosynthesis genes, cell membrane lipidmetabolism genes, and pathogen-plant interaction genes. Importantly,results showed that the "stress memory" can be transferredtransgenerationally, conferring offspring seeds with improved seedgermination and seedling vigor. This may provide an epigenetic breedingstrategy to fortify stress resilience of crops. This nanobiostimulant-basedstress training strategy will increase yield vigor against a changingclimate and will contribute to sustainable agriculture by reducingagrochemical use.