Effect of the 5′-untranslated region on the expression of transgene in liverwort, <i>Marchantia polymorpha</i>

Abstract

Transgenic plants have the potential to provide substantial benefits in the production of pharmaceutical compounds, valuable nutrition, and vaccines. Cauliflower mosaic virus 35S promoter is the most general promoter in higher plants, and also used to express the transgene in liverwort. However, some genes, such as those found in other species, are difficult to express in liverwort. We reported previously that the 5′-untranslated region (UTR) of liverwort ADH-like glucose dehydrogenase gene enhanced transient gene expression in liverwort. In this study, we tested the effects of 5′-UTR on the expression of Gracilaria vermiculophylla cyclooxygenase (GvCOX) gene in stably transformed liverwort. The GvCOX gene encodes the enzyme to produce prostaglandins used as pharmaceutical compounds. Cyclooxygenase activity in transgenic liverwort without 5′-UTR was low, although this mRNA was accumulated. In contrast, addition of the 5′-UTR to the GvCOX gene significantly increased cyclooxygenase activity in transgenic liverwort. We also found that the boundary sequences between the 5′-UTR and GvCOX gene affected mRNA accumulation level. Our system with the 5′-UTR provides a powerful tool for enhancing transgene expression in liverwort.