Isolation and characterization of genes expressed during early events of the dehydration process in the resurrection plant Craterostigma plantagineum

The resurrection plant Craterostigma plantagineum Hochst. (Fam. Scrophulariaceae) is unique in its ability to survive severe desiccation. To analyze the primary response of this plant to drought, genes were identified that are either transiently expressed or down-regulated during early phases of dehydration. A cDNA library was prepared using as template mRNA isolated from 1h dried leaves. The library was differentially screened employing three experimental strategies. Partial sequencing of the isolated cDNAs and comparison of the cDNA sequences with those from the public data bases revealed that 49% of the cDNA clones displayed significant sequence similarity to previously identified genes. Northern and reverse Northern analysis confirmed that all genes so far tested showed differential expression upon drought stress: 58% were transiently expressed, 35.8%, were down-regulated and 6.2% were found to be up-regulated during dehydration. The identification of a large spectrum of differentially expressed genes with diverse cellular functions points to a complex molecular response to drought stress in the resurrection plant C. plantagineum.