A stress-related transcription factor belonging to the YL-1 family is differently regulated in durum wheat cultivars differing in drought sensitivity

The Mediterranean area is characterised by unfavorable environmental conditions such as heat stress and drought responsible for yield loss of crops like durum wheat, widely cultivated in this area. The response of plants to stressing environments is mediated by activation of a complex gene network, strictly related to the genetic background. Among the genes induced by drought, those coding for proteins acting as key regulators of signal transduction are of great interest. Characterization of these genes is a crucial point to understand their potential roles in plant stress response, also in view of their possible use in molecular breeding. In this work we have characterised a Triticum durum gene, named TdDRG1, in two commercial cultivars, Primadur and Svevo, differing for drought stress resistance. TdDRG1 codes for a putative transcription factor belonging to the VPS72/YL-1 family, highly conserved in plants and animals. The expression analysis indicates that this gene is expressed at higher level in roots of the resistant cultivar Svevo, than in the susceptible Primadur. The gene structure was determined in both cultivars and the regulatory activity of 5' upstream regions was analyzed by transient expression analysis using tobacco protoplasts. Dissimilar expression level of TdDRG1 in the two cultivars can be explained by the differences observed in gene structure. In particular, differences in 5' upstream regions could account for contrasting ability to cope with drought of the two cultivars. The data obtained in this study provide indications for further insight into the molecular basis of differences in drought stress response.