Endogenous promoter, 5′-UTR and transcriptional terminator enhance transient gene expression in a liverwort, Marchantia polymorpha L.

Abstract

High expression of transgene is one of the key requirements for the successful establishment of transgenic plants to produce a lot of proteins or metabolites. Although the cauliflower mosaic virus 35S (CaMV35S) promoter and the nopaline synthase (NOS) terminator are often used for this purpose, their efficiencies vary to plant species used. In a liverwort, Marchantia polymorpha L., the CaMV35S promoter and the NOS terminator do not show significant enhancing effect of transgene expression. To construct more efficient gene expression system of the liverwort, we employed the transient gene expression assay system. As a result, the endogenous elongation factor 1a promoter and Flowering locus T1 terminator from the liverwort led to enhance transient gene expression, approximately 75 and 3 times, respectively, compared to the CaMV35S promoter and the NOS terminator. Furthermore, we found that the endogenous 5�-UTR of the liverwort ADH-like UDP glucose dehydrogenase (MpUDP) yielded an enhancement of 15 times greater than in cases without the MpUDP 5�-UTR. These results indicate that DNA elements enhancing gene expression can be obtained efficiently by the transient gene expression assay in a short period of time, promising the application to the transgene expression system for production of proteins and metabolites in the liverwort.