Abstract
Some bryophytes are known to have high desiccation tolerance. In order to clarify the mechanism of the tolerance, we have investigated changes in various photosynthetic activities caused by dehydration using bryophytes grown under different water environments. We found that PSII fluorescence is quenched and the PSII reaction center activity is lost by dehydration, which seems to be important to protect PSII from high light under dry conditions.
It is known that bryophytes have the xanthophyll cycle which protects the cells by inducing nonphotochemical quenching (NPQ) of PSII fluorescence. However, even when the xanthophyll cycle was stopped by dithiothreitol, desiccation-induced NPQ was observed. HPLC analyses suggested that the desiccation-induced NPQ had no relation to the xanthophyll cycle.
Desiccation-tolerant moss, B. argenteum, became less tolerant when it was cultured in a liquid medium, and the responses for desiccation were modified. Acclimation processes to desiccation in cultured B. argenteum will be discussed.
