AbstractBackgroundDrought is one of the most harmful abiotic stresses for plants, leading to reduced productivity of several economically important crops and, consequently, considerable losses in the agricultural sector. When plants are exposed to stressful conditions, such as drought and high salinity, they modulate the expression of genes that lead to developmental, biochemical, and physiological changes, which help to overcome the deleterious effects of adverse circumstances. Thus, the search for new specific gene promoter sequences has proved to be a powerful biotechnological strategy to control the expression of key genes involved in water deprivation or multiple stress responses.ResultsThis study aimed to identify and characterize theGmRD26promoter (pGmRD26), which is involved in the regulation of plant responses to drought stress. The expression profile of theGmRD26gene was investigated by qRT-PCR under normal and stress conditions in Williams 82, BR16 and Embrapa48 soybean-cultivars. Our data confirm thatGmRD26is induced under water deficit with different induction folds between analyzed cultivars, which display different genetic background and physiological behaviour under drought. The characterization of theGmRD26promoter was performed under simulated stress conditions with abscisic acid (ABA), polyethylene glycol (PEG) and drought (air dry) onA. thalianaplants containing the complete construct of pGmRD26::GUS(2.054 bp) and two promoter modules, pGmRD26A::GUS(909 pb) and pGmRD26B::GUS(435 bp), controlling the expression of the β-glucuronidase (uidA) gene. Analysis of GUS activity has demonstrated that pGmRD26and pGmRD26Ainduce strong reporter gene expression, as the pAtRD29positive control promoter under ABA and PEG treatment.ConclusionsThe full-length promoter pGmRD26and the pGmRD26Amodule provides an improveduidAtranscription capacity when compared with the other promoter module, especially in response to polyethylene glycol and drought treatments. These data indicate that pGmRD26Amay become a promising biotechnological asset with potential use in the development of modified drought-tolerant plants or other plants designed for stress responses.