Drought stress increases the accumulation of monoterpenes in sage (<em>Salvia officinalis</em>), an effect that is compensated by elevated carbon dioxide concentration

Abstract

The infliuence of drought stress on the accumulation of cineole, camphor and α/ß-thujone in sage plants (Salvia officinalis L.) was determined by comparing the content of monoterpenes of wellwatered plants and those restricted in irrigation (70% of the optimal water supply). In order to modulate the impact of drought stress, these plants were cultivated either at ambient or elevated CO2 concentrations (385 ppm or 700 ppm). Leaves of sage grown under moderate drought stress reveal significant higher concentrations of monoterpenes (about 33%) than those of plants cultivated under well watered conditions. Under ambient CO2, also the total content of monoterpenes per plant is higher in the stressed plants than in the well-watered ones. The enrichment of the CO2-concentration, which is thought to impair the metabolic effects of drought stress, resulted in a marked decrease in the monoterpene concentration, i.e., 17.8% in the case of well watered plants, and 21.8% in the drought trial. From this it is deduced that the increased reduction capacity arising from drought stress, pushed metabolic activity towards the biosynthesis of highly reduced compounds.