Gene Escape from Glyphosate-Resistant Creeping Bentgrass Fields.
Maria Zapiola, Carol Mallory-Smith, Claudia Campbell, and Marvin Butler. Oregon State University, 107 Crop Science Bldg, Corvallis, OR 97331
Creeping bentgrass (Agrostis stolonifera L.) is a perennial outcrossing grass that can also propagate vegetatively. Main concerns raised by the Oregon seed industry regarding the deregulation of transgenic glyphosate-resistant creeping bentgrass were the contamination of nontransgenic seed crops, the production of resistant weeds through gene flow to compatible species, and the control of glyphosate-resistant creeping bentgrass. Although glyphosate-resistant creeping bentgrass is still under USDA-APHIS regulated status, a 4500 ha seed production control area was established near Madras, OR, and 160 ha were planted with glyphosate-resistant creeping bentgrass in 2002. Surveys were conducted for three consecutive years starting in 2003 to assess the presence and distribution of glyphosate-resistant creeping bentgrass escapes in the control area, and to evaluate the effectiveness of mitigation methods used to remove the escaped plants. Greenhouse experiments were conducted to screen seeds from panicles collected in the control area for glyphosate resistance. While production practices were strictly regulated and monitored to minimize gene escape, evidence of gene flow by pollen was found in 2003 and 2004. In 2005, more than 50% of the over 900 A. stolonifera plants tested were glyphosate resistant. Creeping bentgrass plants were found in locations different than in the previous years. It cannot always be determined whether the gene moved by pollen, seed, or vegetative propagules. However, gene flow by pollen was confirmed in 2005 because 0.047% of 34,007 seedlings tested from seeds collected from susceptible plants were glyphosate-resistant. These results provide evidence that gene flow from creeping bentgrass occurred and the current mitigation program has not been effective in removing all escaped plants.