DIFFERENCES IN REHYDRATION OF 3 DESICCATION-TOLERANT ANGIOSPERM SPECIES

The rehydration characteristics of the desiccation-tolerant plants Cra terostigma wilmsii and Myrothamnus flabellifolia (homoiochlorophyllous ) and Xerophyta viscosa (poikilochlorophyllous) were studied to determ ine differences among them. ii desiccation-sensitive plant (Pisum sati vum) was used as a control. Recovery of water content, quantum efficie ncy (F-V/F-M), photosynthetic pigments and chloroplast ultrastructure as well as damage to the plasmamembrane were studied. P. sativum did n ot recover after desiccation and considerable damage occurred during r ehydration. The desiccation-tolerant plants appeared to differ in thei r responses to dehydration and rehydration. The small herbaceous C. wi lmsii generally showed little damage in the dry state and recovered fa ster than the other tolerant species. M. flabellifolia took longer to recover than C. wilmsii probably due to the presence of a woody stem i n which dehydration-induced xylem embolisms slowed the rate of recover y. The poikilochlorophyllous species X. viscosa took the longest to re cover because it took longer to reconstitute the chloroplasts and the photosynthetic pigments. Quantum efficiency recovered in all species b efore water content and chlorophyll content recovered to control level s. The significance of these different responses to desiccation and re covery from desiccation is discussed. (C) 1996 Annals of Botany Compan y