Skip to main content
Design of chimeric expression elements that confer high-level gene activity in chromoplasts
The Plant Journal (2013)
  • Rodrigo Caroca, Max-Planck-Institut fur Molekulare Pflanzenphysiologie
  • Kate Howell, The University of Notre Dame Australia
  • Claudia Hasse, Max-Planck-Institut fur Molekulare Pflanzenphysiologie
  • Stephanie Ruf, Max-Planck-Institut fur Molekulare Pflanzenphysiologie
  • Ralph Bock, Max-Planck-Institut fur Molekulare Pflanzenphysiologie
Non-green plastids, such as chromoplasts, generally have much lower activity of gene expression than chloroplasts
in photosynthetically active tissues. Suppression of plastid genes in non-green tissues occurs
through a complex interplay of transcriptional and translational control, with the contribution of regulation
of transcript abundance versus translational activity being highly variable between genes. Here, we have
investigated whether the low expression of the plastid genome in chromoplasts results from inherent limitations
in gene expression capacity, or can be overcome by designing appropriate combinations of promoters
and translation initiation signals in the 5′ untranslated region (5′–UTR). We constructed chimeric
expression elements that combine promoters and 5′–UTRs from plastid genes, which are suppressed during
chloroplast-to-chromoplast conversion in Solanum lycopersicum (tomato) fruit ripening, either just at the
translational level or just at the level of mRNA accumulation. These chimeric expression elements were
introduced into the tomato plastid genome by stable chloroplast transformation. We report the identification
of promoter-UTR combinations that confer high-level gene expression in chromoplasts of ripe tomato
fruits, resulting in the accumulation of reporter protein GFP to up to 1% of total cellular protein. Our work
demonstrates that non-green plastids are capable of expressing genes to high levels. Moreover, the chimeric
cis-elements for chromoplasts developed here are widely applicable in basic and applied research using
transplastomic methods.
Publication Date
Citation Information
Caroca R, Howell KA, Hasse C, Ruf S, Bock, R (2013) Design of chimeric expression elements that confer high-level gene activity in chromoplasts. Plant J, 73(3): 368