The ultrastructure of the moss Tortula ruralis on recovery from desiccation

Abstract

The papillose cells of T. ruralis are composed of cytoplasm containing a nucleus, four or five chloroplasts, mitochondria, endoplasmic reticulum, golgi bodies, electron-dense cytoplasmic bodies, and many small vesicles. Their adaxial and abaxial cell walls are composed of two fibrous layers and a cuticle, from which filamentous threads arise. These cells are interconnected by membrane-lined plasmodesmata.Dehydration causes condensation of the protoplasm at the distal and proximal cell ends, rounding and compacting of the chloroplasts, and vesicle disappearance. Immediately upon rehydration the chloroplasts and mitochondria swell and their internal membrane structures are rearranged. However, during a 24-h rehydrating period the cell structure returns to that of the normal hydrated state.