Leaf gas exchange and water relations of the woody desiccation-tolerant during dehydration and rehydration.

Desiccation-tolerant (DT) plants can withstand dehydration to less than 0.1 g HO g dry weight. The mechanism for whole-plant recovery from severe dehydration is still not clear, especially for woody DT plants. In the present study, we evaluated the desiccation tolerance and mechanism of recovery for a potentially new woody resurrection plant (Gesneriaceae). We monitored the leaf water status, leaf gas exchange, chlorophyll fluorescence and root pressure of potted during dehydration and rehydration, and we investigated the water content and chlorophyll fluorescence of leaves in the field during the dry season. After re-watering from a severely dehydrated state, leaf maximum quantum yield of photosystem II of quickly recovered to well-watered levels. Leaf water status and leaf hydraulic conductance quickly recovered to well-watered levels after re-watering, while leaf gas exchange traits also trended to recovery, but at a slower rate. The maximum root pressure in rehydrated was more than twice in well-watered plants. Our study identified as a new DT woody plant. The whole-plant recovery of from extreme dehydration is potentially associated with an increase of root pressure after rehydration. These findings provide insights into the mechanisms of recovery of DT plants from dehydration.