Glutathione status of the bilberry (Vaccinium myrtillus) as a function of plant phenology and artificial herbivory

Abstract

The glutathione status of the deciduous dwarf shrub bilberry (Vaccinium myrtillus L.) was investigated as a function of plant phenology and artificial herbivory. The concentration of the total, reduced, and oxidized glutathione in buds or leaves was determined in control and damaged plants at the time of bud break, flowering, and berry production. Short- and long-term response of the treatment was observed by harvesting the ramets either on the day following or several weeks after the herbivory treatment. There were marked differences in the glutathione status between ramets of different phenological states. More than 90% of glutathione was in the reduced form at bud break and during the flowering period, when the total concentration also peaked. The proportion of the oxidized form increased, up to 80%, in autumn, when the level of total and reduced glutathione had decreased. Reduced glutathione was possibly needed in reactions of protein synthesis during the active growth period, whereas it may have been translocated to storage tissues before winter. Herbivory treatment had no significant effect on glutathione status, either on the short or the long time scale. Possible reasons for this unexpected result are discussed. The observed pattern in the glutathione status is compared with other studies that investigated the phenology of the bilberry. Key words: glutathione, herbivory, phenology, Vaccinium.