Desiccation and rehydration dynamics in the epiphytic resurrection fern Pleopeltis polypodioides

The epiphytic resurrection-or desiccation-tolerant (DT)-fern Pleopeltis polypodioides can survive extreme desiccation and recover physiological activity within hours of rehydration. Yet, how epiphytic DT ferns coordinate between deterioration and recovery of their hydraulic and photosynthetic systems remains poorly understood. We examined the functional status of the leaf vascular system, chlorophyll fluorescence, and photosynthetic rate during desiccation and rehydration of P. polypodioides. Xylem tracheids in the stipe embolized within 3-4h during dehydration. When the leaf and rhizome received water, tracheids refilled after similar to 24h, which occurred along with dramatic structural changes in the stele. Photosynthetic rate and chlorophyll fluorescence recovered to predesiccation values within 12h of rehydration, regardless of whether fronds were connected to their rhizome. Our data show that the epiphytic DT fern P. polypodioides can utilize foliar water uptake to rehydrate the leaf mesophyll and recover photosynthesis despite a broken hydraulic connection to the rhizome.

Automated summary

The epiphytic resurrection-or desiccation-tolerant fern Pleopeltis polypodioides can survive extreme desiccation and recover physiological activity within hours of rehydration. The study found that xylem tracheids in the stipe embolized during dehydration but refilled after rehydration along with structural changes in the stele. Photosynthetic rate and chlorophyll fluorescence of the fern recovered quickly after rehydration, despite a broken hydraulic connection to the rhizome.