gas generated from air by atmospheric-pressure plasma device*

We developed a plasma device which can produce high-concentration dinitrogen pentoxide (N₂O₅) gas from air, which is poorly understood in biological function. Here, we analyzed the effect of N₂O₅ gas on plant immunity using model plant Arabidopsis thaliana. First, A. thaliana was exposed to N₂O₅ gas and then inoculated with Botrytis cinerea, a fungal pathogen. After 2 days inoculation, significant reduction in lesion size of B. cinerea was observed in N₂O₅-gas-exposed plants compared to air-control, suggesting that disease resistance was enhanced by N₂O₅ gas. To examine changes in gene expression of defense-related genes, RNA-seq and qRT-PCR was performed using N₂O₅-gas-exposed plants. Gene Ontology analysis based on the RNA-seq results revealed that the signaling pathways for jasmonic acid (JA) and ethylene, phytohormones important for plant immunity, was activated by N₂O₅ gas exposure. In addition, qRT-PCR analysis showed that N₂O₅ gas exposure transiently activated gene expression involved in biosynthesis of antifungal substances. In JA signaling mutant, furthermore, B. cinerea resistance induced by N₂O₅ gas was compromised. Our results suggest that N₂O₅ gas generated from air plasma is available for development of environmentally friendly technology for plant disease control.