Sequence and expression variation in the dehydrin6 gene in barley varieties contrasting in response to drought stress
Dehydrins (Dhns) are the Group II Late Embryogenesis Abundant (LEA) proteins that are thought to play a key role in the response to abiotic stresses in plants. In the present study, a dehydrin6 (Dhn6) gene was isolated and characterized from eight barley genotypes (Hordeum vulgare L.) of diverse geographic origins, representing a wide range of drought tolerance. Based on analysis of physiological traits, the drought tolerance of Tunisian and Jordanian varieties and the drought sensitivity of European varieties (United Kingdom) were confirmed.To elucidate the involvement of the Dhn6 gene in the adaptive processes, its expression level was investigated under drought stress conditions. The results indicated that Tunisian and Jordanian genotypes displayed an early and rapid induction of Dhn6 expression while the UK varieties showed a delay in responding by up-regulation. Changes in expression of the Dhn6 gene, encoding a protein of unknown function, were shown to be associated with drought response mechanisms of the different genotypes.Furthermore, a multiple alignment of coding sequences of Dhn6 genes of the eight barley varieties was conducted. Two types of variation were observed in the UK varieties sequences; a deletion of 62 bp (segment ɸ) and six amino acid substitutions. Accordingly, we speculate that the observed variability in sequence and in expression of Dhn6 could be linked to the adaptability of barley to drought.