Isolation and functional characterization of a novel rice constitutive promoter

Key message: A novel rice constitutive promoter (P) was isolated. The molecular mechanism of the promoter activity was investigated. Pcould be used as an alternative constitutive promoter for crop transgenic engineering. Monocot constitutive promoter is an important resource for crop transgenic engineering. In this report, we isolated a novel promoter, Oscon1 promoter (P), from the 5′ upstream region of a constitutively expressed rice gene OsDHAR1. In P::GUS transgenic rice, we showed that P had a broad expression spectrum in all tested tissues. The expression of the promoter was further analyzed in comparison with the previously characterized strong constitutive promoters. P exhibited comparable activity to OsCc1, OsAct1 or ZmUbi promoters in most tissues, and more active than 35S promoter in roots, seeds, and calli. Further quantitative assays indicated that P activity was not affected by developmental stages or by environmental factors. Further, 5′-deletions analysis indicated that the distinct regions might contribute to the strong expression of P in different tissues. Overall, our results suggest that P is a novel constitutive promoter, which could potentially use in transgenic crop development.