It should be noted that the cross talk between the JA and SA signalling pathways might also be modified by the pathogens infection to some extent, as expression induction of PI I and PI II by NPR1 silencing were generally lower in elevated [CO2] compared with ambient [CO2], in normal control, P. syringae-, or B. cinerea-inoculated plants (Figs 6, 8, 9). The gene discussed is NPR1; the disease is infection.