WASHINGTON-Concerned that genetically modified plants will spread their genes to related crops in nearby fields, researchers have developed a system aimed at preventing such crossbreeding.

It's a method they hope that with further refinement, will allow farmers to reseed crops yearly without worry about affecting nonmodified crops.

The new system, developed by a team of researchers led by Johann P. Schenthaner at Canada's Eastern Cereal and Oilseed Research Center in Ottawa, is reported in the online edition of Proceedings of the National Academy of Sciences.

While the system was developed using tobacco, Schernthaner said he believes it would be applicable for the most crops, although "the genetic components involved would have to be assessed for suitability on a case to case basis."

The findings do show, he said, "the containment of transgenes is possible in an agricultural setting and that environmental concerns can be addressed in a simple fashion."

Doug Gurain-Sherman, science director for biotechnology at the Center for Science in the Public Interest, said there 'are pros and cons to this from our perspective" but it is technology that should be explored as a means of preventing gene movement.

Agronomy professor T. Wayne Pfeiffer of the University of Kentucky said that while the system worked to some degree, the process used seemed "impractical in a seed production system for a seed reproduced crop."

While the system has been demonstrated in the laboratory, the researchers said it needs to be refined and tested thoroughly for actual field use.