SiO2 nanoparticle–based seed priming enhances lettuce seed germination and seedling growth under heat stress

● SiO 2 NP-based priming improves lettuce seeds vigor under normal conditions (20 °C) and heat stress (30 °C) . ● Nanopriming triggers physiological and transcriptional reprogramming of lettuce. ● SiO 2 NP-based seed priming has a sustained effect on seedlings heat stress responses. Lettuce ( Lactuca sativa L.), a nutritious green vegetable cultivated and consumed globally, is a cool-season crop with an optimal growth temperature range of 15°C–25°C. Elevated temperatures adversely affect lettuce seed vigor, plant growth, and productivity by influencing membrane permeability, enzyme activity, photosynthetic capacity, and gene expression. Therefore, developing technology to enhance lettuce thermotolerance represents a critical challenge for adapting to global warming. Here, we used the silica nanoparticles (SiO 2 NPs)-based priming technology for lettuce seeds and found that SiO 2 NP priming (10 mg/L) substantially enhanced seed germination and seedling performance under heat stress (30°C). Transcriptional analysis revealed that genes associated with energy metabolism, plant hormone metabolism, and abiotic stress signaling pathways (e.g., MAPK and calcium signaling) were markedly activated in SiO 2 NP-primed seeds, likely contributing to superior germination under heat stress (30°C). Interestingly, SiO 2 NP priming also improved seedling thermotolerance by activating similar stress signaling pathways, suggesting that seeds treatment with SiO 2 NPs generates a long-lasting stress response in lettuce. Overall, SiO 2 NP-based seed priming improves lettuce seed and seedling performance under heat stress, achieved through triggering abiotic stress signaling pathways followed by regulation of genes encoding heat-shock factors and heat-shock protein.