XVI International Botanical Congess

Studies of gene expression during environmental stress are commonly used to screen for genes, which may play a role in stress tolerance. We are using Fucus vesiculosus as a model to identify desiccation-responsive genes. Subtracted cDNA libraries were constructed for algae undergoing mild (20-30% tissue water loss) and severe desiccation (70-80% tissue water loss). Clones obtained are being screened for differential expression under desiccated and non-desiccated conditions in the following ways: 1) Hybridisation to southern blots of PCR-amplified cDNA from desiccated and non-desiccated tissue, and 2) Northern analysis. Clones of interest were sequenced and compared to known protein sequences in a database. Using this approach, several transcripts with homology to known genes have been identified. The results suggest that mild desiccation and high irradiance increases the transcription of several genes involved in photosynthesis (e.g., chloroplast ATP synthase, PSI and PSII core proteins). Other genes putatively identified following severe desiccation are involved in the detoxification of active oxygen species, transcriptional regulation, and protein turnover. These preliminary findings nevertheless suggest that molecular tools may find important applications in the study of the molecular, cellular and physiological basis of desiccation tolerance in fucoid algae, and in studies of interspecific and population-level variations in stress-tolerance.