An Exploration of Medicago truncatula as a Platform for the Production of Heterologous Proteins

Abstract

Plant molecular farming refers to the process of utilising plants as bioreactors to produce high value proteins, including enzymes, antibodies, and other therapeutic molecules. Almost all molecular farming initiatives employ Nicotiana benthamiana as a host plant. Herein, we investigated the potential of a model legume, Medicago truncatula, as an alternative platform for synthesis of heterologous protein. We exploited well established methodologies developed for the study of root endosymbioses to genetically transform M. truncatula root systems via Agrobacterium rhizogenes. The suitability of M. truncatula as a platform for the production of heterologous proteins was then examined through the cultivation of composite plants and immortalised root organ cultures (ROCs) that accumulate recombinant Green fluorescent protein (GFP). Our results demonstrate that recombinant GFP accumulates at high levels in composite M. truncatula plants up to 15 weeks post-transformation. Immortalised ROC lines continue to accumulate recombinant GFP beyond 57 weeks post-transformation. Purification of recombinant GFP from ROCs resulted in yields of 780 mg/kg and 194 mg/kg of root tissue, respectively. Sustained accumulation of high levels of recombinant GFP accordingly demonstrate the potential of M. truncatula as a viable alternative platform for heterologous protein production.