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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Crop Bioprotection Research » Research » Publications at this Location » Publication #184362
Title: GENETICALLY ENGINEERED RESISTANCE TO ORGANOPHOSPHATE HERBICIDES PROVIDES A NEW MARKER SYSTEM FOR TRANSGENIC MAIZE

Author
item Pinkerton, Terrence
item HOWARD, JOHN - TX A&M UNIV, COLL.STA.TX
item WILD, JAMES - TX A&M UNIV, COLL.STA.TX

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2007
Publication Date: N/A
Citation: N/A

Interpretive Summary: Organophosphate hydrolase (OPH) was tested as a potential marker gene in transgenic maize. The objective was to demonstrate if the wide range of OPH substrates, including herbicides, could be used to select plants expressing OPH. Plant marker systems currently use antibiotic resistance, or resistance to common herbicides. Concerns about environmental escape and consumer acceptance have driven research into alternative marker systems. OPH was tested as both a selectable marker (i.e., resistance to herbicides) and as a scorable marker (i.e., a visual indication of the genes presence). The presence of the gene in plant tissue was easily scored with compounds that generate fluorescent or colored products after degradation by OPH. The transgenic plants also showed resistance to herbicidal compounds in tissue culture and in the greenhouse. Results indicate that OPH may be a viable alternative marker system for use in plant biotechnology.

Technical Abstract: Organophosphate hydrolase (OPH encoded by opd) provides a new scorable genetic marker system for use in plant cell culture and regenerated plant tissue. OPH hydrolyzes a wide range of substrates that create visually detectable compounds whose hydrolysis can be readily observed and quantified in biological tissues. When OPH activity is expressed in Zea mays, it is possible to distinguish between transgenic and non-transgenic tissues. A variety of different OP compounds were tested as screenable substrates which can be used with various plant tissues in order to generate a wide range of screening compounds. For example, transgenic leaf tissue was easily differentiated from non-transgenic leaf tissue by a simple colorimetric assay with the OP coroxon. In addition, the transformation of callus and intact whole seed could be easily distinguished using a novel non-destructive imbibing method which allowed the callus or seed to grow and/or germinate after scoring. In addition to using OPH as a scorable marker with various OP pesticides, the OP herbicide bensulide and OP pesticide haloxon proved to be positive selection agents for germinating seeds and callus tissue respectively.