Differences in Rehydration of Three Desiccation-tolerant Angiosperm Species

The rehydration characteristics of the desiccation-tolerantplantsCraterostigma wilmsii andMyrothamnus flabellifolia (homoiochlorophyllous)andXerophyta viscosa (poikilochlorophyllous) were studied todetermine differences among them. A desiccation-sensitive plant(Pisum sativum) was used as a control. Recovery of water content,quantum efficiency (F_V/F_M), photosynthetic pigments and chloroplastultrastructure as well as damage to the plasmamembrane werestudied. P. sativum did not recover after desiccation and considerabledamage occurred during rehydration. The desiccation-tolerantplants appeared to differ in their responses to dehydrationand rehydration. The small herbaceousC. wilmsii generally showedlittle damage in the dry state and recovered faster than theother tolerant species.M. flabellifolia took longer to recoverthanC. wilmsii probably due to the presence of a woody stemin which dehydration-induced xylem embolisms slowed the rateof recovery. The poikilochlorophyllous speciesX. viscosa tookthe longest to recover because it took longer to reconstitutethe chloroplasts and the photosynthetic pigments. Quantum efficiencyrecovered in all species before water content and chlorophyllcontent recovered to control levels. The significance of thesedifferent responses to desiccation and recovery from desiccationis discussed. Desiccation-tolerant; F_V/F_M; homoiochlorophyllous; poikilochlorophyllous; chlorophyll; chloroplast; ultrastructure; Craterostigma wilmsii ; Myrothamnus flabellifolia ; Xerophyta viscosa ;Pisum sativum