Jumping Genes to Remove Markers from GM Plants

Over the past few years, consumer and environmental groups have expressed concern about the use of markers in genetic improvement of crops. Marker genes are used in plant transformation systems to select transgenic events. However, they are no longer needed after the transgenic plants are regenerated. Until recently, scientists have devised several ways to produce marker-free transgenic crops. One such strategy is the use of jumping genes. Jumping genes or transposons are so called because they have the ability to move around to different positions within the genome in a cell.

Using the maize transposon Ac system, scientists from the National Taiwan University have developed a strategy for efficiently removing the marker genes from transgenic plants. The scientists modified the selectable marker esps gene (for glyphosate tolerance) for expression in rice by introducing it to a gene carrier with the salicylic acid inducible jumping genes attached to it.  After rice transformation, glyphosate-tolerant rice lines were selected and exposed to salicylic acid.  Since the marker gene is attached to the transposon, the activation of the jumping gene resulted to the truncation of the selectable marker gene.

The abstract of the paper published by Molecular Breeding is available at http://www.springerlink.com/content/6720mj4607787451/?p=3c79ad37742f4e4fa77130f361884de7&pi=4 Subscribers can read the full text at http://www.springerlink.com/content/6720mj4607787451/fulltext.pdf