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

Exposure to N ₂ O ₅ generated by plasma technology activates immunity in Arabidopsis through tryptophan metabolites. However, little is known about the effects of N ₂ O ₅ exposure on other plant species. Sweet basil synthesizes many valuable secondary metabolites in its leaves. We therefore performed metabolomic analyses at three different levels exposure levels to assess the effects of N ₂ O ₅ on basil leaves. The results showed that cinnamaldehyde increased in a dose-dependent manner, accompanied by transcriptional activation of the cinnamoyl-CoA reductase CCR2 gene. Phenolic acids also increased with increasing doses. Certain flavonoids, columbianetin, and caryophyllene oxide increased with lower Ex1 exposure, cineole and methyl eugenol increased with moderate Ex2 exposure and L-glutathione GSH also increased with higher Ex3 exposure. Furthermore, N ₂ O ₅ altered jasmonic acid signaling in a dose-dependent manner. These results suggest that N ₂ O ₅ exposure increases several valuable secondary metabolites in sweet basil leaves via plant defense responses in a controllable system.