Starch breakdown at night linked to plant drought resistance
Crassulacean acid metabolism (CAM) is an adaptation found in certain desert-dwelling plants that allows them to take up CO2 at night to avoid water loss through transpiration. Two processes have been identified as being important in regulating CAM: the availability of starch, and the plant's internal clock. A project titled 'Temporal regulation of starch degradation in CAM plants' (CAMSTAR) was funded by the EU to investigate the unique molecular pathways and processes that control CAM. The project focused on the genetics of a model CAM plant, Kalanchoe fedtschenkoi. Several enzymes known to be important in starch degradation were investigated by artificially modifying the genes that code for them. The research showed that CAM plants favoured a different method of starch degradation to the one used by non-CAM plants. Investigations into the internal clock genes of K. fedtschenkoi revealed that a functioning clock is a critical control mechanism of nocturnal starch breakdown. Plants that suffered a deficiency in certain clock genes were unable to adjust the rate of starch degradation in response to changes in the length of a dark period. The CAMSTAR team thus provided deeper insights into how these plants cope with dry conditions. Understanding the mechanisms that plants use to avoid water stress is an important step towards engineering drought-resistant crops.
