Strong seed-specific protein expression from the Vigna radiata storage protein 8SGα promoter in transgenic Arabidopsis seeds
•Few Vigna seed promoter sequences have been reported.•A new 8SGα promoter that conferred seed-specific expression in Arabidopsis was identified.•The 8SGα promoter strength was observed to be higher than the conventional 35S CaMV promoter in seeds.•This 8SGα promoter provides an additional choice for the expression of multiple proteins in seeds.
Vigna radiata (mung bean) is an important crop plant and is a major protein source in developing countries. Mung bean 8S globulins constitute nearly 90% of total seed storage protein and consist of three subunits designated as 8SGα, 8SGα′ and 8SGβ. The 5′-flanking sequences of 8SGα′ has been reported to confer high expression in transgenic Arabidopsis seeds. In this study, a 472-bp 5′-flanking sequence of 8SGα was identified by genome walking. Computational analysis subsequently revealed the presence of numerous putative seed-specific cis-elements within. The 8SGα promoter was then fused to the gene encoding β-glucuronidase (GUS) to create a reporter construct for Arabidopsis thaliana transformation. The spatial and temporal expression of 8SGα∷GUS, as investigated using GUS histochemical assays, showed GUS expression exclusively in transgenic Arabidopsis seeds. Quantitative GUS assays revealed that the 8SGα promoter showed 2- to 4-fold higher activity than the Cauliflower Mosaic Virus (CaMV) 35S promoter. This study has identified a seed-specific promoter of high promoter strength, which is potentially useful for directing foreign protein expression in seed bioreactors.
Journal: Journal of Biotechnology - Volume 174, 20 March 2014, Pages 49–56