Phenotypic plasticity of Iris pumila leaf functional traits in response to experimental warming

Abstract

Plant physiology, fitness and distribution largely depend on temperature, hence it is expected that global warming will extensively alter their biodiversity as well as the ecosystem functioning. Variations in plant functional traits are widely used to predict the impact of global warming on vegetation, as they usually reflect the plant’s adaptive strategies to essential environmental resources, including temperature. To assess how plants respond to climate warming, we investigated the phenotypic expression of two major leaf functional traits, specific leaf area (SLA) and stomatal density (SD), to a temperature rise of 1°C. A total of 40 Iris pumila genotypes, which were consistently cultivated in a growth room at baseline temperature (23/19°C day/night), were exposed to elevated temperature (24/20°C day/night). Within each temperature treatment, the last fully developed leaf was harvested from every genotype and analyzed for the SLA and SD. The mean value of both investigated traits increased significantly with temperature. Leaves developed under elevated temperature exhibited 7% greater SLA and 22% higher SD compared to those developed under ambient temperature. These results suggest that I. pumila plants are able to counteract rising temperatures by the plastic response of SLA and SD. Such a capacity to acclimate its major leaf functional traits to altered temperature conditions may provide I. pumila a resilience to climate warming that will be occurring within its natural habitats.