Physiological responses to water deficit and changes in leaf cell wall composition as modulated by seasonality in the Brazilian resurrection plant Barbacenia purpurea

Resurrection plants are able to tolerate the extreme desiccation of their vegetative tissues and after the increase of water availability recover their full metabolic capacity. This capacity that depends on the regulatory mechanisms that allow metabolism occurs under low water potential until the anabiosis state. The responses to the desiccation process in Barbacenia purpurea (Velloziaceae), a resurrection plant commonly found in rock outcrops in Rio de Janeiro, Brazil, start when leaf water relative content decreases below 70%. In this work, we studied the influence of total water withholding on physiological and metabolic parameters during desiccation of B. purpurea under winter and summer conditions. Throughout the desiccation process of B. purpurea, morphological alterations such as subtle leaf curling and osmotic adjustment were observed in both winter and summer seasons. Increased uronic acid content in the leaf cell walls also occurred in response to water suppression in both seasons. Despite some fluctuations, no significant differences in antioxidant activity during dehydration/rehydration were observed. Our findings indicate that the mechanisms implicated in desiccation tolerance in this species are governed by leaf water status and that the intensity of physiological and metabolic responses is modulated by seasonality due to the amplitude of the environmental changes in each season.