Gene structure and expression analysis of the drought- and abscisic acid-responsive CDeT11-24 gene family from the resurrection plant Craterostigma plantagineum Hochst.

In order to understand the molecular mechanisms which are responsible for desiccation tolerance in the resurrection plant Craterostigma plantagineum Hochst. a thorough analysis of the CDeT11-24 gene family was performed. CDeT11-24 comprises a small gene family whose genes are expressed in response to dehydration, salt stress and abscisic acid (ABA) treatment in leaves. The gene products are constitutively expressed in roots and disappear only when the plants are transferred to water. It is therefore suggested that the proteins are involved in sensing water status. The predicted proteins are very hydrophilic; they share some features with late-embryogenesis-abundant proteins, and sequence similarities were found with two ABA- and drought-regulated Arabidopsis genes. The analysis of beta-glucuronidase reporter genes driven by the CDeT11-24 promoter showed high activity in mature seeds in both transgenic Arabidopsis and tobacco. In vegetative tissues the promoter activity in response to ABA was restricted to young Arabidosis seedlings. The responsiveness to ABA during later developmental stages was regained in the presence of the Arabidopsis gene product ABI3. Dehydration-induced promoter activity was only observed in Arabidopsis leaves at a particular developmental stage. This analysis indicates that some components in the signal transduction pathway of the resurrection plant are not active in tobacco or Arabidopsis.