CHARACTERIZATION OF GLUTATHIONE S-TRANSFERASES IN NEEDLES OF NORWAY SPRUCE TREES FROM A FOREST DECLINE STAND

Glutathione S-transferases (GST) detoxify many electrophilic xenobioti cs, including several volatile organic compounds and pesticides. The G ST activity for the conjugation of several xenobiotic substances was i solated from needles of Norway spruce (Picea abies L. Karst.) trees fr om a forest decline stand in the northern alps. Trees that exhibited d ifferent degrees of damage were selected from several stands in an alt itude profile. The GST activity toward 1-chloro-2,4-dinitrobenzene (CD NB) in crude protein extracts of needles showed a seasonal pattern wit h highest activity during summer. The GST activity exhibited a strong dependence on the altitude of the stand showing highest activities in trees growing in the valley and lowest activities in trees growing in the summit regions of the mountain. When cytosolic GST from needles of healthy and damaged trees was purified, trees of healthy appearance e xhibited three distinct GST isozymes with activities for the conjugati on of CDNB and 1,2-dichloro-4-nitrobenzene (DCNB), whereas severely de foliated trees exhibited four GSTs with additional activity for the co njugation of ethacrynic acid. The main GST isozymes catalyzing the con jugation of CDNB differed in molecular weight, isoelectric point and c atalytic properties between damaged and healthy trees.