The resurrection plant Craterostigma plantagineum tolerates an extreme loss of cellular water. Therefore this plant is being studied as model system to analyse desiccation tolerance at the molecular level. Upon dehydration, new transcripts are abundantly expressed in different tissues of the plant. One such desiccation-related nuclear gene (dsp-22 for desiccation stress protein) encodes a mature 21 kDa protein which accumulates in the chloroplasts. Sequence analysis indicates that dsp-22 is closely related to early light inducible genes (Elip) of higher plants and to a carotene biosynthesis related gene (cbr) isolated from the green alga Dunaliella bardawil. In contrast to other desiccation-related genes, light is an essential positive factor regulating the expression of dsp-22: ABA-mediated gene activation leads to the accumulation of the transcript only in the presence of light. During the desiccation process, light acts at the transcriptional and post-transcriptional levels. The implications of these different controls and the possible role of the dsp-22 protein in the desiccation/rehydration process are discussed.