When water availability is low, two Mediterranean Salvia species rely on root hydraulics

Increase in severity and frequency of drought events is altering plant community composition, exposing biomes to higher risk of biodiversity losses. This is exacerbated in the most fragile areas as Mediterranean biome. Thus, identifying plant traits for forecasting species with a high risk of drought-driven mortality is particularly urgent. In the present study we investigated the drought resistance strategy of two Mediterranean native species: Salvia ceratophylloides Ard. (Sc) and Salvia officinalis L. (So) by taking into account the impact of drought-driven water content decline on plant hydraulics. Well-watered samples of Sc displayed higher leaf and stem satured water content, lower shoot biomass than So samples but similar root biomass. In response to drought, Sc showed a conservative water use strategy, as the prompt stomatal closure and leaves shedding suggested. A drought-tolerant mechanism was confirmed in So samples. Nevertheless, Sc and So showed similar drought-driven plant hydraulic conductance (Kplant) recover ability. Root hy-draulic traits played a key role to reach this goal. Relative water content as well as loss of cell rehydration capability and membrane damages, especially of stem and root, were good proxy of drought-driven Kplant decline.