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.

Nematode Uptake Preference toward Different Nanoplastics through Avoidance Behavior Regulation

“…Reactive oxygen species (ROS) production is an indicator of cytotoxicity, which has been reported being involved in nanoplastics' toxicity. 40,41 After the 72 h exposure, the superoxide dismutase (SOD) content was higher in all PS-NP treatments than that of the control (Figure 4b and Figure S13, P < 0.001), and the GSH content was also decreased upon the PS-100 (0.1 and 1.0 mg/L, P < 0.001) and PS-500 (1.0 mg/L, P < 0.001) treatments in comparison with that of the control (Figure 4b and Figure S13), suggesting that all PS-NPs induced oxidative stress in nematodes. Further study suggested that the exposure to PS-NPs triggered growth inhibition and increased the mortality of nematodes (Figure 4b and Figure S13).…”

Seed Priming with Silver Ions Improves Growth and Physicochemical Features of Rice Plants (Oryza sativa L.) under Copper Stress

“…Ag + -Priming Promotes ROS Production in Rice Seeds. According to Zhao et al, 15,16 we hypothesized that reactive oxygen species (ROS) play an important role in triggering defense responses against Cu in rice. The EPR spectrum revealed more obvious signals of • OH in Ag +priming seeds (Figure S7a).…”

“…13−15 Seed priming acts as a "vaccine" to produce ROS as a signaling molecule to reprogram the metabolism and transcriptome of a plant, thereby enhancing plant resistance to biotic and abiotic stresses during growth. 15,16 Seed priming can effectively reduce the uptake of heavy metals in plants by modulating the expression of heavy metal transporter proteins and enhancing antioxidant enzyme activities. For example, ZnO-NP seed priming improved the growth of rice and reduced Cd uptake by increasing the activity of antioxidant enzymes and altering alanine, aspartic acid, and glutamic acid metabolism, while SiNPs improved the growth of wheat and reduced the Cd content by increasing the activity of antioxidant enzymes.…”

“…Recent studies reported that AgNPs priming enhanced rice resilience to salt, blast disease, and cold stress, with lasting effects throughout the rice growth cycle. 15,16 The application of lower doses of AgNPs during rice growth promoted tillering and resulted in significant increases in grain yield and aboveground biomass. 26 Addition of Ag + to the medium of tissue culture inhibits ethylene secretion and increases plant secondary metabolites, thereby promoting plant root growth.…”