GLUTATHIONE STATUS AND GLUTATHIONE-REDUCTASE ACTIVITY IN SPRUCE NEEDLES OF HEALTHY AND DAMAGED TREES AT 2 MOUNTAIN SITES

Levels of glutathione, in both reduced and oxidized form, and glutathi one reductase activity were monitored in needles of healthy and damage d spruce trees (Picea abies (L.) Karst.) during the course of four veg etation periods at two natural sites. The glutathione content and glut athione reductase activity showed a pronounced annual rhythm in undama ged trees, whereas damaged spruce trees deviated significantly from th is course. In comparison with undamaged trees, damaged trees showed ma rkedly increased levels of glutathione during the test period of 1989- 1991. However, glutathione reductase activity differed in damaged and undamaged trees, only in 1989-1990. The ratio of reduced to oxidized g lutathione (GSH/GSSG ratio) was slightly higher in damaged trees, and the highest levels were found during the winter months. In the case of damaged trees, a correlation between GSH/GSSG ratio and current ozone levels at the sites could be clearly established. The present results indicate that, damaged trees suffer from increased oxidative stress, especially in the period from June to October.