The Role of Dreb2 Gene in Drought Tolerance of Common Wheat (Triticum Aestivum L.) Associated with Azospirillum Brasilense

Abstract

Dehydration causes loss of wheat (Triticum aestivum L.) yield. Inoculation of wheat with Azospirillum brasilense improves its tolerance to drought. Although up-regulation of DREB2 gene has increased drought tolerance of wheat, less information exists about DREB2 expression under inoculation with A. brasilense. In this study, the physiological responses of different pairs of six wheat cultivars with A. brasilense Sp7 and Sp245 strains were evaluated to drought and the tolerant (Roshan-Sp245), sensitive (Shahpasand-Sp7), moderately tolerant (Roshan-Sp7) and moderately sensitive pairs (Shahpasand-Sp245) were selected. Afterward, in the second experiment, DREB2 expression of the selected pairs was evaluated under inoculation and/or dehydration (psi(w) = -90 MPa) at 0, 120 and 360 minutes. At 120 min, DREB2 expression was more in the tolerant and moderately tolerant pairs than others and also higher in inoculated and/or dehydration conditions. Root's DREB2 was up-regulated almost 700-fold in the tolerant and moderately tolerant pairs under dehydration. In contrast, in the sensitive cv., DREB2 expression did not change due to dehydration or inoculation. This could be the effect of compatibility or homology of A. brasilense strains and wheat cultivars which affected DREB2 expression. Therefore, DREB2 expression had a significant effect on increased drought tolerance in tolerant and moderately tolerant pairs.