Ectopic transplastomic expression of a synthetic MatK gene leads to cotyledon-specific leaf variegation

Yujiao Qu, Julia Legen, Jürgen Arndt, Stephanie Henkel, Galina Hoppe, Christopher Thieme, Giovanna Ranzini, Jose M. Muino, Andreas Weihe, Uwe Ohler, Gert Weber, Oren Ostersetzer, Christian Schmitz-Linneweber*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Chloroplasts (and other plastids) harbor their own genetic material, with a bacterial-like gene-expression systems. Chloroplast RNA metabolism is complex and is predominantly mediated by nuclear-encoded RNA-binding proteins. In addition to these nuclear factors, the chloroplast-encoded intron maturase MatK has been suggested to perform as a splicing factor for a subset of chloroplast introns. MatK is essential for plant cell survival in tobacco, and thus null mutants have not yet been isolated. We therefore attempted to over-express MatK from a neutral site in the chloroplast, placing it under the control of a theophylline-inducible riboswitch. This ectopic insertion of MatK lead to a variegated cotyledons phenotype. The addition of the inducer theophylline exacerbated the phenotype in a concentration-dependent manner. The extent of variegation was further modulated by light, sucrose and spectinomycin, suggesting that the function of MatK is intertwined with photosynthesis and plastid translation. Inhibiting translation in the transplastomic lines has a profound effect on the accumulation of several chloroplast mRNAs, including the accumulation of an RNA antisense to rpl33, a gene coding for an essential chloroplast ribosomal protein. Our study further supports the idea that MatK expression needs to be tightly regulated to prevent detrimental effects and establishes another link between leaf variegation and chloroplast translation.

Original languageAmerican English
Article number1453
JournalFrontiers in Plant Science
Volume9
DOIs
StatePublished - 4 Oct 2018

Bibliographical note

Publisher Copyright:
© 2018 Qu, Legen, Arndt, Henkel, Hoppe, Thieme, Ranzini, Muino, Weihe, Ohler, Weber, Ostersetzer and Schmitz-Linneweber.

Keywords

  • Chloroplast
  • MatK
  • Nicotiana tabacum
  • Splicing
  • Transplastomic
  • Variegation

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