Isolation of the 3β-HSD promoter from Digitalis ferruginea subsp. ferruginea and its functional characterization in Arabidopsis thaliana

Background Although members of the SDR gene family (short chain dehydrogenase) are distributed in kingdom of life, they have diverse roles in stress tolerance mechanism or secondary metabolite biosynthesis. Nevertheless, their precise roles in gene expression or regulation under stress are yet to be understood. Methods As a case study, we isolated, sequenced and functionally characterized the 3 beta-HSD promoter from Digitalis ferruginea subsp. ferruginea in Arabidopsis thaliana. Results The promoter fragment contained light and stress response elements such as Box-4, G-Box, TCT-motif, LAMP element, ABRE, ARE, WUN-motif, MYB, MYC, W box, STRE and Box S. The functional analysis of the 3 beta-HSD promoter in transgenic Arabidopsis seedlings showed that the promoter was expressed in cotyledon and root elongation zone in 2 days' seedlings. However, this expression was extended to hypocotyl and complete root in 6 days' seedlings. In 20 days-old seedlings, promoter expression was distributed to the whole seedling including hydathodes aperture, vascular bundle, shoot apical meristem, trichomes, midrib, leaf primordia, hypocotyl and xylem tissues. Further, expression of the promoter was enhanced or remained stable under the different abiotic stress conditions like osmotic, heat, cold, cadmium or low pH. In addition, the promoter also showed response to methyl jasmonate (MeJA) application. The expression could not be induced in wounded cotyledon most likely due to lack of interacting elements in the promoter fragment. Conclusions Taken together, the 3 beta-HSD promoter could be a candidate for the development of transgenic plants especially under changing environmental conditions.

Automated summary

Although members of the SDR gene family are widely distributed in different kingdoms of life, their roles in gene expression and regulation under stress conditions are not fully understood. In this study, we isolated and functionally characterized the 3 beta-HSD promoter from Digitalis ferruginea and examined its expression in Arabidopsis thaliana. The promoter showed stable expression under different abiotic stress conditions and responded to methyl jasmonate application. These findings suggest that the 3 beta-HSD promoter could be a potential candidate for the development of transgenic plants, particularly under changing environmental conditions.