Expression Analysis of Stress-Related genes involved in the response of Durum wheat to salinity and high light

The study of stress-related genes is critical to understand the molecular mechanisms of stress tolerance in plants. Several studies have demonstrated the important role of asparagine synthetase, glutamate decarboxylase and Δ1 -pyrroline-5-carboxylate synthase genes signalling in response to environmental stresses. In order to investigate the expression changes of these genes in durum wheat under salinity and high light, a semi-quantitative RT-PCR analysis was performed. High light increased the gene expression level of TdAsn1 alone (2.6 fold) and in combination with salinity (2 fold) in comparison with the control at low light. The isoforms TdAsn2 was expressed at low levels compared to TdAsn1 and the transcript was present only in leaves in control conditions or simultaneous stresses . A trend similar to that of TdAsn1 was observed for P5CS expression. On the contrary, GAD expression was decreased by salinity and high light (1.1 and 1.5-fold, respectively) and even more under the two combined stresses (3.7 fold) compared to control. The expression levels were compared to the respective enzymatic activities. Our expression data confirmed the pivotal role of the studied genes in the response to abiotic stresses in durum wheat.