Planta

, Volume 220, Issue 6, pp 864–874

Targeted site-directed mutagenesis of a heme oxygenase locus by gene replacement in the moss Ceratodon purpureus

  • Gerhard Brücker
  • Franz Mittmann
  • Elmar Hartmann
  • Tilman Lamparter
Original Article

DOI: 10.1007/s00425-004-1411-6

Cite this article as:
Brücker, G., Mittmann, F., Hartmann, E. et al. Planta (2005) 220: 864. doi:10.1007/s00425-004-1411-6

Abstract

The moss Physcomitrella patens is so far the only plant species in which it is possible for nuclear genes to be modified by homologous recombination at a reasonably efficiency. Here we describe the use of homologous recombination for another moss, Ceratodon purpureus. Our approach is based on the repair of the ptr116 mutant allele. In this mutant, codon 31 of the heme oxygenase gene CpHO1 is mutated to a stop codon. Heme oxygenase is necessary for the conversion of heme to biliverdin, the precursor of the phytochrome chromophore. Thus, in ptr116 the phytochrome-mediated responses of phototropism, chlorophyll accumulation and branching are lost. Protoplast transformation with DNA encoding the wild-type protein resulted in a rescue of 0.8% of regenerated protoplasts. In about half of the analyzed lines, formation of CpHO1 concatemers was observed at the CpHO1 locus, whereas in the other half, the mutant CpHO1 gene was replaced by a single DNA copy. This gene repair led to the exchange of single bases, and thus provides the first demonstration of efficient site-directed mutagenesis in a plant nuclear genome. Our studies also revealed an effective mechanism for gene inactivation in Ceratodon. When wild-type protoplasts were transformed with intact or modified CpHO1 genes, approximately 40% of regenerated protoplasts showed the ptr phenotype.

Keywords

Ceratodon Gene targeting Heme oxygenase Homologous recombination Photomorphogenesis Phytochrome 

Abbreviations

GFP

Green fluorescent protein

GT

Gene targeting

HO

Heme oxygenase

HR

Homologous recombination

PCB

Phycocyanobilin

ptr

Phototropism

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Gerhard Brücker
    • 1
  • Franz Mittmann
    • 2
  • Elmar Hartmann
    • 1
  • Tilman Lamparter
    • 1
  1. 1.PflanzenphysiologieFreie Universität BerlinBerlinGermany
  2. 2.PflanzenphysiologieJustus Liebig Universität GiessenGiessenGermany

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