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[SANET-MG] defense against stray transgenic pollen



4 July 2005
Prof. Joe Cummins
A conventional  genetic defense against transgene pollution in maize
	
The major problem with genetically modified (GM) crops has been the pollution of conventional crops by the spread of pollen and seeds which pollute the conventional crop with undesirable transgenes. A little effort has been made to provide isolation boundaries which are intended to limit spread of the GM pollen but these boundaries have not proved effective. A recent patent by Thomas Hoegemeyer from Hooper ,Nebraska, Method for producing field corn seed and plants (United States Patent 6,875,905 April 5,2005) provides a conventional genetic to transgene pollution in maize. The invention provides for a method of producing hybrid corn seed and grain which are either free of contamination or pollination from outside sources or have a dramatically reduced pollination from outside sources. The genetic restriction was selected from pop corn which requires extensive sorting if contaminated with pollen from. field or sweet corn. Pop corn lines were established that would not set seed if pollinated by field or sweet corn but in a reciprocal cross the popcorn would pollinate field or sweet corn. The process is called non-reciprocal cross incompatibility. The genetic basis for is a linked multiple allelic at the ga locus on chromosome 4 of maize. The dominant allele Ga.sup.s/Ga.sup.s will not set seed with ga (field corn) pollen but will set seed with Ga.supp.s pollen. Plants which are ga/ga will set seed with ga or Ga.sup.s pollen. When ga and Ga.supp.s pollen are competing in ga/Ga.supp.s styles, only the Ga.supp.s pollen tubes effect fertilization. The invention acknowledged that Ga.supp.s is ,in nature, linked to poor roots and stalks and it has proved difficult to move the gene into field corn without a performance drag along with the difficulty in making crosses. However the invention does provide stray pollen protection for a crop . Both endosperm and embryo are protected from stray pollen. It seems likely that the poor performance drag may be overcome by fuller conventional genetic selections. The patent includes one peculiar application, it was suggested that maize modified with pharmaceutical genes would be protected from stray field corn pollen. The field corn really should be protected from the pharmaceutical maize but it is very unwise to release pharmaceutical maize that can fertilize field corn but cannot be fertilized by field corn. A patent neither requires nor demands proof of performance in the field. It will be indeed wonderful if the pollen incompatibility system provides complete protection from stray pollen. However, realistically, some degree of stray pollen leakage may occur in a range of environmental conditions. Nevertheless, the approach is promising and may provide a useful way to protect conventional maize from GM crops.
	
	
	
	

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