AgNPs-Triggered Seed Metabolic and Transcriptional Reprogramming Enhanced Rice Salt Tolerance and Blast Resistance

Abstract

Seeds are facing harsher environments due to the changing climate. Improving seeds' stress resilience is critical to reduce yield loss. Here, we propose that using ROS-generating nanoparticles (NPs) to prestimulate seeds would enhance the stress resilience of seeds and seedlings through triggering stress/immune responses. We examined this hypothesis by exposing AgNPs-primed rice (Oryza sativa L.) seeds under salt conditions (NaCl). The results showed that primed seeds exhibit accelerated germination speed, increased seedling vigor (from 22.5 to 47.6), biomass (11%), and root length (83%) compared to seeds with hydropriming treatment. Multiomics (metabolomics and transcriptomics) analyses reveal that AgNPs-priming triggered metabolic and transcriptional reprogramming in rice seeds. Signaling metabolites, such as salicylic acid, niacinamide, and glycerol-3-phosphate, dramatically increased upon AgNPs-priming. KEGG pathway analysis reveals that AgNPs-priming activated stress signaling and defense related pathways, such as plant hormone signal transduction, glutathione metabolism, flavone and flavonol biosynthesis, MAPK signaling pathway, and plant−pathogen interaction. These metabolic and transcriptional changes indicate that AgNPs-priming triggered stress/immune responses. More importantly, this "stress memory" can last weeks, providing protection to rice seedlings against salt stress and rice blast fungus (Magnaporthe oryzae). Overall, we show that prestimulated seeds with ROS-generating AgNPs not only enable faster and better germination under stress conditions, but also increase seedling resistance to biotic and abiotic stresses. This simple nanobiostimulant-based strategy may contribute to sustainable agriculture by maintaining agricultural production and reducing the use of pesticides.

Biochar nanoparticles alleviate salt stress in tomato (Solanum lycopersicum) seedlings

“…31 It was found that Ag NPs restimulate seeds, which would enhance the salt stress resilience of seeds and seedlings through triggering stress/ immune responses. 32 And in a previous report, we found that biochar NPs improved rice resistance to ferulic acid which is the major allelochemical from invasive plants. 29 And it is confirmed that nanomaterials have a high surface area to volume ratio, which makes them attractive for adsorbing chemicals onto their surface via van der Waals forces, electrostatic interactions, or chemical bonding.…”

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

“…Our recent studies have demonstrated that AgNPs can penetrate the seed coat and enter into rice seed tissues, catalyzing ROS generation during the training process . However, whether AgNPs enter rice leaves and catalyze ROS production during leaf training is unknown.…”

“…Our recent studies have demonstrated that AgNPs can penetrate the seed coat and enter into rice seed tissues, catalyzing ROS generation during the training process. 54 However, whether AgNPs enter rice leaves and catalyze ROS production during leaf training is unknown. Previous studies have demonstrated that nanoparticles in the size range of ∼50−70 nm are able to enter into leaves through leaf stomata and cuticular pathways.…”

Silica nanoparticle accumulation in plants: current state and future perspectives

“…61 Additionally, seed germination is initiated by water absorption (imbibition) through small pores in the seed coat, such that SiO 2 NPs may enter seeds as a suspension in the imbibed water. 62 SiO 2 NPs that have entered seeds may subsequently be transported from the roots to the buds during plant growth. The penetration and translocation of SiO 2 NPs in the radicle, root, and leaf tissues of SiO 2 NP-primed seedlings have been demonstrated using SEM.…”