Analysis and regulation of gene expression in the resurrection plant Craterostigma plantagineum

Abstract

Plant responses to water loss are very complex and depend on the severity of the water loss as well as on the developmental stage and the physiological condition of the affected plants. To study responses to protoplastic dehydration at the molecular level we initiated research with the objective to identify gene products which may contribute to water stress tolerance. The unique ability of resurrection plants to withstand severe water loss greater than 90% make them a suitable system to study water stress tolerance: upon rewatering these plants recover quickly from the stress (Gaff 1971, Bartels et al. 1990). We have chosen Craterostigma plantagineum as a representative of the resurrection plants for our studies. An attractive feature of this resurrection plant is that we can analyse desiccation tolerance in undifferentiated callus tissue, too. Callus withstands rapid dehydration if it is treated with the plant hormone abscisic acid (ABA) prior to the drying treatment (Bartels et al. 1990). This makes two experimental systems available from the same plant for the isolation of molecular components relevant to desiccation. Initially we isolated a large number of cDNA clones which are induced upon dehydration and/or ABA treatment (Bartels et al. 1990, Piatkowski et al. 1990, Bartels et al. 1992). The purpose of this chapter is to summarize some characteristic structural and regulatory features of the expressed genes.