F an inhibitor of flavincontaining oxidascs, or K252a(0.5 AM), a general inhibitor of protein kinases. 3 h later, plants were exposed to 200(tomato) or 400 n L L 1 ozone(Arabidopsis) for 5 h. Leaves were infiltrated after 8 h with DAB or NBT as abovc: visible injury was assesscd after 48 h.