Engineering Climate-Resilient Rice Using a Nanobiostimulant-based “Stress Training” Strategy

Abstract Under a changing climate, cultivating climate-resilient crops will be critical to maintaining food security. Here, we propose the application of ROS-generating nanoparticles as nanobiostimulants to trigger stress/immune responses, and subsequently increase the stress resilience of plants. We established three regimens of AgNPs-based “stress training”: seed priming (SP), leaf priming (LP), and combined seed- and leaf- priming (SLP). Trained rice seedlings were then exposed to either rice blast fungus ( M. oryzae .) or chilling stress (10 ºC). The results show that all “stress training” regimes, particularly SLP significantly enhanced the resistance of rice against the fungal pathogen (lesion size reduced by 82% relative to un-trained control). SLP training also significantly enhanced rice tolerance to cold stress. Under cold conditions, SLP training significantly increased leaf biomass by 35% compared to controls. The mechanisms for the enhanced resilience were investigated with metabolomic and transcriptomic profiling, which show that “stress training” induced considerable metabolic and transcriptional reprogramming in rice leaves. AgNPs-boosted ROS activated stress signaling pathways by oxidative post-translational modifications of stress related kinases, hormones, and transcriptional factors (TFs). These signaling pathways subsequently modulated the expression of defense genes, including specialized metabolites (SMs) biosynthesis genes, cell membrane lipid metabolism genes, and pathogen-plant interaction genes. These AgNPs-triggered metabolic and transcriptional reprogramming enable rice plants to mount a more rapid and intense response to future stresses. This nanobiostimulant-based strategy for increasing the stress resilience of crops will increase yield vigor against a changing climate and will contribute to sustainable agriculture by reducing agrochemical use.