OpenPlant PI Jim Haseloff recently published collaborative work with colleagues from the University of Cambridge, China and the USA describing a new system for expressing high concentrations of protein in the chloroplasts of the simple plant system Marchantia polymorpha. Their work provides a new tool for plant based production of biomolecules, with cholorplasts providing the potential for very heigh levels of transgene expression.

Construction of DNA Tools for Hyperexpression in Marchantia Chloroplasts

Eftychios Frangedakis, Fernando Guzman-Chavez, Marius Rebmann, Kasey Markel, Ying Yu, Artemis Perraki, Sze Wai Tse, Yang Liu, Jenna Rever, Susanna Sauret-Gueto, Bernard Goffinet, Harald Schneider, Jim Haseloff.

ACS Synth Biol. 2021 Jul 16;10(7):1651-1666

https://doi.org/10.1021/acssynbio.0c00637

ABSTRACT

Chloroplasts are attractive platforms for synthetic biology applications since they are capable of driving very high levels of transgene expression, if mRNA production and stability are properly regulated. However, plastid transformation is a slow process and currently limited to a few plant species. The liverwort Marchantia polymorpha is a simple model plant that allows rapid transformation studies; however, its potential for protein hyperexpression has not been fully exploited. This is partially due to the fact that chloroplast post-transcriptional regulation is poorly characterized in this plant. We have mapped patterns of transcription in Marchantia chloroplasts. Furthermore, we have obtained and compared sequences from 51 bryophyte species and identified putative sites for pentatricopeptide repeat protein binding that are thought to play important roles in mRNA stabilization. Candidate binding sites were tested for their ability to confer high levels of reporter gene expression in Marchantia chloroplasts, and levels of protein production and effects on growth were measured in homoplastic transformed plants. We have produced novel DNA tools for protein hyperexpression in this facile plant system that is a test-bed for chloroplast engineering.