Influence of stress history on the response of the dioecious plant Urtica dioica L. to abiotic stress

Background: Reaching maturity is thought to affect plant responses to stress, but few studies have examined thus far how stress periods during the juvenile phase can alter the response of plants in a mature stage, particularly in dioecious plants. Aims: This study tested the hypothesis that sex and stress history can alter the response of Urtica dioica plants to abiotic stress. Methods: Stress indicators (water content, chlorophylls, the Fv/Fm ratio and the extent of lipid peroxidation) were measured in leaves of juvenile and mature plants exposed to a combination of water and nutrient deficit, with an emphasis on evaluating the effects of stress during the juvenile phase on the stress response of mature plants. Results: Stress treatment during the juvenile phase affected plant response to stress during the mature phase. Leaves of reproductive shoots were the most sensitive to stress history, as shown by increases in lipid peroxidation in leaves of reproductive shoots relative to non-reproductive ones. Leaves of both shoot types responded similarly in males and females, which showed no significant differences in any of the parameters measured. Conclusions: Stress history appears to determine the response of mature U. dioica plants to abiotic stress, plants with a stress history showing acclimation to subsequent stress, leaves of non-reproductive shoots of both males and females being more stress tolerant and allowing plant survival under severe stress.