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Keywords:

  • feral;
  • gene flow;
  • genetically modified organisms;
  • hybridization;
  • naturalized

Ecologists have paid close attention to environmental effects that fitness-enhancing transgenes might have following crop-to-wild gene flow (e.g. Snow et al. 2003). For some crops, gene flow also can lead to legal problems, especially when government agencies have not approved transgenic events for unrestricted environmental release. Creeping bentgrass (Agrostis stolonifera), a common turfgrass used in golf courses, is the focus of both areas of concern. In 2002, prior to expected deregulation (still pending), The Scotts Company planted creeping bentgrass with transgenic resistance to the herbicide glyphosate, also known as RoundUp®, on 162 ha in a designated control area in central Oregon (Fig. 1). Despite efforts to restrict gene flow, wind-dispersed pollen carried transgenes to florets of local A. stolonifera and A. gigantea as far as 14 km away, and to sentinel plants placed as far as 21 km away (Watrud et al. 2004). Then, in August 2003, a strong wind event moved transgenic seeds from windrows of cut bentgrass into nearby areas. The company’s efforts to kill all transgenic survivors in the area failed: feral glyphosate-resistant populations of A. stolonifera were found by Reichman et al. (2006), and 62% of 585 bentgrass plants had the telltale CP4 EPSPS transgene in 2006 (Zapiola et al. 2008; Fig. 2). Now, in this issue, the story gets even more interesting as Zapiola & Mallory-Smith (2012) describe a transgenic, intergeneric hybrid produced on a feral, transgenic creeping bentgrass plant that received pollen from Polypogon monspeliensis (rabbitfoot grass). Their finding raises a host of new questions about the prevalence and fitness of intergeneric hybrids, as well as how to evaluate the full extent of gene flow from transgenic crops.

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Figure 1.  Creeping bentgrass and rabbitfoot grass occur along canals and irrigation ditches within the designated control area near Madras, Oregon. Photo courtesy of M. L. Zapiola.

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Figure 2.  A feral, glyphosate-resistant creeping bentgrass plant established along a ditch within the control area. Photo courtesy of M. L. Zapiola.

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