GENERATION OF FREE-RADICALS IN GERMINATING NORWAY SPRUCE - DIFFERENCES IN THE EFFECT OF 2 DIFFERENT PHENOLIC-COMPOUNDS

We have studied the defences of Norway spruce seeds against pollutants during germination, using two different phenolic compounds, 5-OH-1,4- naphthoquinone (5-OH-NQ)(3) and 2,4,5-trichlorophenoxyacetic acid (2,4 ,5-T). Only small effects of 5-OH-NQ on germination of seeds were obse rved at concentrations up to 200 mu M, which could be explained by the formation of a less reactive metabolite of 5-OH-NQ. These results sug gest that Norway spruce seeds have a very effective defence system aga inst quinone and quinone-derived reactive oxygen species. The effect o f 2,4,5-T on seed germination was, however, more pronounced, resulting in an abnormal growth of the seedlings. This behaviour was probably d ue to a strong increase in ethylene production (10-fold) in these seed lings. Also fatty acyl-CoA oxidase activity, a peroxisomal enzyme of b eta-oxidation that catalyses the formation of H2O2, was found to incre ase 6.9-fold in seedlings germinated in presence of 2,4,5-T. A strong decrease in the activity of photosystem II and an increase in lipid pe roxidation in chloroplasts was also observed.