Seasonality of Glutathione Dynamics in Scots Pine and Bilberry

Abstract

Seasonal changes in the glutathione status of Scots pine (Pinus sylvestris L.) needles and bilberry (Vaccinium myrtillus L.) stems and leaves were investigated during 1995 and 1997-1998, respectively. The glutathione concentration, the proportion of reduced glutathione (GSH%) and glutathione reductase (GR) activity were measured at monthly intervals throughout one year. The glutathione concentration and GSH% in current year's Scots pine needles were highest during late summer, but decreased during autumn. It is suggested that exchange reactions between free and protein-bound glutathione may be involved in this reduction. Both metabolites decreased towards summer in the previous year's needles. GR activity exhibited the lowest values in summer and the highest values in winter in both needle generations. In bilberry stems, glutathione peaked during midwinter, while GSH% remained high and relatively constant throughout the year. GR activity was highest in August, after which it gradually declined. In bilberry leaves, the total glutathione concentration was high in early summer. This peak was followed by a sharp decrease during midsummer. GR activity in the leaves was very low, but showed a clear increase towards autumn. Obviously, glutathione metabolism showed considerable seasonal variation in Scots pine needles and in bilberry leaves and stems, but the pattern of variation differed between the studied species and organs.

Key words

Bilberry - glutathione - glutathione reductase - Pinus sylvestris - Scots pine - seasonal changes - Vaccinium myrtillus