Desiccation-induced ultrastructural and biochemical changes in the leaves of the resurrection plant Myrothamnus flabellifolia

Abstract

Light microscopy and low-temperature scanning electron microscopy were used to systematically compare the surface and internal ultrastructures of hydrated and desiccated leaves of the resurrection plant Myrothamnus flabellifolia (Welw.). This revealed that leaf tissue underwent considerable shrinkage and collapse on desiccation but was supported by a framework of vascular and sclerenchymous tissue, which is responsible for the fan-like shape of the leaves. In addition, the leaf ribs were covered with wax and an internal wax cuticle was observed. Biochemical analysis showed that the cyanidin 3-glucoside content increased on desiccation as did the trehalose and sucrose contents. Salt deposits were observed at the apices of desiccated leaves in the proximity of hydathode-like structures. We propose that this might regulate the leaf salt content since decreased intracellular cation concentration was observed in desiccated leaves. We believe that these unique adaptations contribute to the remarkable desiccation-tolerance properties of this plant.