Essentials of the Living World 5th Edition by George Johnson

Exercise 4

Can Modified Genes Escape from GM Crops?
On page 237, the question of whether gene flow of GM crops posed a problem to the environment was discussed. A field experiment conducted in 2004 by the Environmental Protection Agency assessed the possibility that introduced genes could pass from genetically modified golf course grass to other plants. Investigators introduced a gene conferring herbicide resistance (the EPSP synthetase gene for resistance to glyphosate) into golf course bentgrass, Agrostis stolonifera, and then looked to see if the gene passed from the GM grass to other plants of the same species, and also if it passed to other related species.
The map at the bottom displays the setup of this elaborate field study. A total of 178 A. stolonifera plants were placed outside the golf course, many of them downwind. An additional 69 bentgrass plants were found to be already growing downwind, most of them the related species A. gigantea. Seeds were collected from each of these plants, and the DNA of resulting seedlings tested for the presence of the gene introduced into the GM golf course grass. In the graph, the upper red histogram (a histogram is a "bar graph" that sorts data into a series of discontinuous categories, the value of each bar representing the number of individuals in a category, or, as in this case, the average value of entries in that category) presents the relative frequency with which the gene was found in A. stolonifera plants located at various distances from the golf course. The lower blue histogram does the same for A. gigantea plants.
Drawing Conclusions Is it fair to conclude that genetically modified traits can pass from crops to other plants? What qualifications would you place on your conclusion?