Characterization of cDNAs encoding Triticum durum dehydrins and their expression patterns in cultivars that differ in drought tolerance

From a cDNA library prepared from roots of Triticum durum water-stressed seedlings, we have characterized four dehydrin clones. Two clones, pTd27e and pTd16, code for proteins with classical features of dehydrins, i.e. the consensus motif KIKEKLPG that is present beyond the tract of serine residues and at the carboxy terminus. The encoded proteins, Tddhn15 and Tddhn16, show similarities with Triticum aestivum sequences. Two clones, pTd25a and pTd38, code for a dehydrin which lacks the stretch of serine residues and shows sequence similarity to T. aestivum Cor proteins. To correlate T. durum drought tolerance with dehydrin gene expression, we have for four cultivars compared the accumulation of dehydrin transcripts in roots and shoots of seedlings in response to a water-stress, and under application of exogenous ABA. A water-stress time course showed that accumulation of the dehydrin transcripts is delayed in the drought-tolerant cultivars. Also, the level of accumulated transcripts appeared to be greater in the drought-tolerant cultivars than in the drought-sensitive cultivar. A similar result was observed after application of exogenous ABA.