| Abstract: | The resurrection plant (Craterostigma plantagineum) is desiccation tolerant. However, callus derived from this plant, when propagated in vitro, requires exogenously applied
abscisic acid (ABA) in order to survive desiccation. Treatment of callus tissue with ABA induces most of the genes that are
induced by dehydration in the whole plant. This property has been exploited for the isolation of mutants that show dominant
phenotypes resulting from the ectopic expression of endogenous genes induced by the insertion of a foreign promoter. Here
we describe new T-DNA tagged Craterostigma desiccation-tolerant (cdt) mutants with different molecular and physiological characteristics, suggesting that different pathways of desiccation tolerance
are affected. One of the mutants, cdt-2, constitutively expresses known osmoprotective Lea genes in callus and leaf tissue. Further analysis of this mutant revealed that the tagged locus is similar to a previously
characterised gene, CDT-1, which codes for a signalling molecule that confers desiccation tolerance. The nature of the T-DNA insertion provides insight
into the mechanism by which the CDT-1/2 gene family functions in ABA signal transduction. |
