Elimination of marker genes from transformed filamentous fungi by unselected transient transfection with a Cre-expressing plasmid

Simona Florea, Kalina Andreeva, Caroline Machado, Peter M. Mirabito, Christopher L. Schardl

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


A convenient method to remove selectable markers from fungal transformants permits the markers to be used for sequential transformations, and should also reduce public concerns and regulatory impediments to applications involving environmental release of genetically modified fungi. We report a method for marker removal that requires no genetic selection. Protoplasts from Neotyphodium coenophialum, Neotyphodium uncinatum and Epichloë festucae transformants containing a hygromycin B phosphotransferase gene (hph) flanked by loxP sites in direct orientation were transiently transfected with a Cre-recombinase expression plasmid, and then cultured without selection. The marker was eliminated in 0.5-2% of the colonies, leaving a single loxP sequence and no other exogenous DNA in the genome. This approach was also applied to the yA gene of Aspergillus nidulans as a laboratory exercise to demonstrate multiple principles of transformation and genome manipulation. Thus, the Cre-expression plasmid and transient transfection approach was rapid, flexible and useful for diverse filamentous fungi.

Original languageEnglish
Pages (from-to)721-730
Number of pages10
JournalFungal Genetics and Biology
Issue number10
StatePublished - Oct 2009

Bibliographical note

Funding Information:
We thank Walter Hollin for technical support, and the University of Kentucky Advanced Genetic Technologies Center for DNA sequencing. Funding was provided by US Department of Agriculture Grants 2005-35319-16141, 2007-10021743, and 2008-35318-04549. Work by PMM was supported by the Gertrude Flora Ribble endowment to the University of Kentucky Department of Biology. This is Kentucky Agricultural Experiment Station publication number 09-12-074 published with the approval of the director.


  • Aspergillus nidulans
  • Cre-lox
  • Epichloë
  • Ergot alkaloids
  • Fungal transformation
  • Gene disruption
  • Hygromycin B-resistance
  • Marker excision
  • Neotyphodium
  • dmaW
  • yA

ASJC Scopus subject areas

  • Microbiology
  • Genetics


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