The chloroplast transformation toolbox: selectable markers and marker removal
Article first published online: 23 MAR 2011
© 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd
Plant Biotechnology Journal
Special Issue: Chloroplast Biotechnology
Volume 9, Issue 5, pages 540–553, June 2011
How to Cite
Day, A. and Goldschmidt-Clermont, M. (2011), The chloroplast transformation toolbox: selectable markers and marker removal. Plant Biotechnology Journal, 9: 540–553. doi: 10.1111/j.1467-7652.2011.00604.x
- Issue published online: 6 MAY 2011
- Article first published online: 23 MAR 2011
- Received 8 November 2010; revised 29 January 2011; accepted 31 January 2011.
- plastid transformation;
- Chlamydomonas reinhardtii;
- Nicotiana tabacum
Plastid transformation is widely used in basic research and for biotechnological applications. Initially developed in Chlamydomonas and tobacco, it is now feasible in a broad range of species. Selection of transgenic lines where all copies of the polyploid plastid genome are transformed requires efficient markers. A number of traits have been used for selection such as photoautotrophy, resistance to antibiotics and tolerance to herbicides or to other metabolic inhibitors. Restoration of photosynthesis is an effective primary selection method in Chlamydomonas but can only serve as a screening tool in flowering plants. The most successful and widely used markers are derived from bacterial genes that inactivate antibiotics, such as aadA that confers resistance to spectinomycin and streptomycin. For many applications, the presence of a selectable marker that confers antibiotic resistance is not desirable. Efficient marker removal methods are a major attraction of the plastid engineering tool kit. They exploit the homologous recombination and segregation pathways acting on chloroplast genomes and are based on direct repeats, transient co-integration or co-transformation and segregation of trait and marker genes. Foreign site-specific recombinases and their target sites provide an alternative and effective method for removing marker genes from plastids.