Cytological changes during desiccation and rehydration of the desiccation-tolerant moss Tortula ruralis

This study investigates the effects of desiccation and rehydration on leaf cells in the desiccation-tolerant moss, Tortula ruralis. Desiccation causes extensive cellular changes the protoplast collapses and condenses at the proximal and distal cell ends. The cytoplasm becomes filled with numerous small vesicles and vacuoles, which replace the large central vacuole. The organization of organelles is lost and several become rounded. Upon rehydration, over 12-24 hours, there is re-fusion of the vesicles/vacuoles, which gradually leads to the re-establishment of the large central vacuole(s). This process coincides with the recovery of normal cytoarchitecture. Further, 4-D live-imaging of these changes to desiccation has revealed hitherto uncharacterized links between the structure of the cytoplasm and the dynamics of the vacuolar membrane. The results indicate a key role for the vacuoles in protecting cellular integrity throughout desiccation and rehydration, which may facilitate the rapid recovery of cytoarchitecture.