Activation of plant immunity by exposure to dinitrogen pentoxide gas generated from air using plasma technology

Abstract

Reactive nitrogen species (RNS) play an important role in plant immunity as signaling factors. We previously developed a plasma technology to partially convert air molecules into dinitrogen pentoxide (N2O5), an RNS whose physiological action is poorly understood. To reveal the function of N2O5 gas in plant immunity, Arabidopsis thaliana was exposed to plasma-generated N2O5 gas once (20 s) per day for 3 days, and inoculated with Botrytis cinerea, Pseudomonas syringae pv. tomato DC3000 (Pst), or cucumber mosaic virus strain yellow (CMV(Y)) at 24 h after the final N2O5 gas exposure. Lesion size with B. cinerea infection was significantly (P < 0.05) reduced by exposure to N2O5 gas. Propagation of CMV(Y) was suppressed in plants exposed to N2O5 gas compared with plants exposed to the air control. However, proliferation of Pst in the N2O5-gas-exposed plants was almost the same as in the air control plants. These results suggested that N2O5 gas exposure could control plant disease depending on the type of pathogen. Furthermore, changes in gene expression at 24 h after the final N2O5 gas exposure were analyzed by RNA-Seq. Based on the gene ontology analysis, jasmonic acid and ethylene signaling pathways were activated by exposure of Arabidopsis plants to N2O5 gas. A time course experiment with qRT-PCR revealed that the mRNA expression of the transcription factor genes, WRKY25, WRKY26, WRKY33, and genes for tryptophan metabolic enzymes, CYP71A12, CYP71A13, PEN2, and PAD3, was transiently induced by exposure to N2O5 gas once for 20 s peaking at 1–3 h post-exposure. However, the expression of PDF1.2 was enhanced beginning from 6 h after exposure and its high expression was maintained until 24–48 h later. Thus, enhanced tryptophan metabolism leading to the synthesis of antimicrobial substances such as camalexin and antimicrobial peptides might have contributed to the N2O5-gas-induced disease resistance.

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

“…The signi cant induction of JA-related gene expression in the indirectly exposed leaves (Fig. 5), together with the fact of JA/ET signaling pathway activation shown in the previous study 59 , suggests that N 2 O 5 gas exposure induces an ISR-like systemic response. Some reports discuss SA/JA crosstalk, where SA-and JA-mediated signaling interact with each other antagonistically or synergistically depending on the conditions [63][64][65] .…”

“…a few years ago58 , in addition to existing plasma synthesis of O 3 and NO/NO 2 from air. Furthermore, the activation effects of APP-synthesized N 2 O 5 gas on plant immunity were demonstrated through pathogen inoculation tests on N 2 O 5 -stimulated plants, indicating its potential as a new technology for the control of plant diseases59 . However, the biological mechanisms by which plants respond to dinitrogen pentoxide at a fundamental physiological level remain poorly understood.…”

Utilizing plasma-generated N2O5 gas from atmospheric air as a novel gaseous nitrogen source for plants

“…4 F, G). Moreover, it was recently reported that exposure of Arabidopsis thaliana to N 2 O 5 gas leads to the induction of an immune response during a pathogen inoculation test (Tsukidate et al 2022 ). This indicates that N 2 O 5 is absorbed by the surface of the plant tissue.…”

Increase of secondary metabolites in sweet basil (Ocimum basilicum L.) leaves by exposure to N2O5 with plasma technology

“…In other words, N 2 O 5 does not have the residual properties found in other chemicals. Furthermore, exposure to N 2 O 5 gas activates plant immunity and suppresses both Botrytis cinerea infection and propagation of Cucumber mosaic virus strain yellow in Arabidopsis 4 . Besides, several genes involved in jasmonic acid (JA) and ethylene signaling pathways and the synthesis of secondary metabolites from tryptophan metabolism are immediately activated by N 2 O 5 exposure in Arabidopsis 4 , 5 .…”