Induction of systemic resistance through calcium signaling in Arabidopsis exposed to air plasma-generated dinitrogen pentoxide

Abstract Plasma technology, which can instantaneously transform air molecules into reactive species stimulating plants, potentially contributes to the development of a sustainable agricultural system with high productivity and low environmental impact. In fact, plant immunity activation by exposure to a reactive gas mainly consisting of dinitrogen pentoxide (N₂O₅) was recently discovered, while physiological responses to N₂O₅ are rarely known. Here, we demonstrate early physiological responses to N₂O₅ in Arabidopsis. Exposure to N₂O₅ gas induced an increase in cytosolic Ca²⁺ concentration within seconds in directly exposed leaves, followed by systemic long-distance Ca²⁺-based signaling within tens of seconds. In addition, jasmonic acid (JA)-related gene expression was induced within 10 minutes, and a significant upregulation of the defense-related gene PDF1.2 was observed after 1 day of exposure to N₂O₅ gas. These systemic resistant responses to N₂O₅ were found unique among air-plasma-generated species such as ozone (O₃) and nitric oxide (NO)/nitrogen dioxide (NO₂). Our results provide new insights into understanding of plant physiological responses to air-derived reactive species, in addition to facilitating development of plasma applications in agriculture.