Nitrogen dioxide (NO2) - induced signaling in Arabidopsis thaliana: NO2 provides basal pathogen resistance or induces a hypersensitive response-like cell death

At high concentrations, the air pollutant nitrogen dioxide is known to be harmful to plants. This work revealed that high doses of NO2 (30 ppm for 1h) induced the accumulation of nitrite, NO, and H2O2 which were primarily responsible for the cell death in Arabidopsis. The work further demonstrated that non-damaging doses of NO2 (10 ppm for 1h) increased Arabidopsis´ resistance against B. cinerea and P. syringae by stimulating an enhanced deposition of callose. The NO2-induced B. cinerea resistance was dependent on functional PAD3, and JA- and SA-mediated signaling.