| Abstract/Contents: | "Since the Williamette Valley produces nearly all the bentgrass (Agrostis spp.) seed grown in the United States and exports bentgrass seed in large quantities to Europe, risks associated with the commercial production of transgenic cultivars in the major grass seed production area of the world must be defined. Creeping bentgrass (Agrostis stolonifera L.) can be a serious weed in other crops. Since creeping bentgrass may be the first perennial, wind pollinated, outcrossing, transgenic grass species to be produced commercially, essential data must be generated on pollen movement within the crop. Pollen flow, viability, pollination and seed formation are all sensitive to climatic parameters, which differ greatly from region to region, so it is imperative that this research be conducted where the crop will be commercially cultivated. The two primary objectives of this study were to investigate intra- and interspecific gene flow of transgenic creeping bentgrass in the Williamette Valley of Oregon. Pollen movement was determined by placing transects of non-transgenic creeping bentgrass around a nursery of 286 transgenic plants genetically engineered for tolerance to the herbicide glufosinate. Approximately 250 non-transgenic creeping bentgrass plants were planted in transects around the transgenic nursery in 1998 and 1999 near Hubbard, OR. In 1998, the following transects were established: 1) two circles around the nursery at 109 (33.2 m) and 272.5 ft (83.1 m) with plants spaced at 50 ft (15.24 m) and 100 ft (30.48 m), respectively; and 2) two line transects aligned with prevailing winds (NE) with one transect NE 244 ft (74.4 m) and the SW transect 370 ft (112.8 m) from the edge of the nursery based on Oregon Seed Certification isolation distances, which is 165-300 ft (50.3 - 91.4 m) (depending upon field size) for certified seed production. In 1999, the length of the line transects were increased to the following: 1) SW transect, 978 ft (298.1 m); 2) NE transect, 268 ft (81.7 m); 3) SE transect, 612 ft (186.5 m); and 5) NW transect, 319 ft (97.2 m). Using non-linear regression, the following distances were predicted for transgenic pollen introgression to the 0.02% level. In 1998, along the SW transect, transgenic pollen traveled 3,500 ft (1,066.8 m) and along the NE transect it traveled 4,296 ft (1,309.4 m). In 1999, the transgenic pollen was estimated to have traveled 1,022 ft (331.5 m) to the SW, 1,892 ft (576.7 m) to the NE, 861 ft (262.4 m) to the NW, and 1,022 ft (331.5 m) to the SE. The second part of the study was to evaluate interspecific hybridization in creeping bentgrass for its propensity to hybridize freely. Twelve species of bentgrass has been documented as occuring in the area of bentgrass seed production. Six are naturalized species and are part of a complex that freely hybridize: A. canina L., A. capillaris L., A. castellana Boiss & Reuter, A. gigantea Roth, A. stolonifera, and A. vinealis Schreber. Accessions of A. canina, A. capillaris, A. castellana, A. curtissii, A. gigantea, A. pallens, and A. sp. were placed in the transgenic nursery prior to flowering and allowed to interpollinate. The crossing experiments resulted in the introgression of the bar gene from creeping bentgrass into A. canina, A. capillaris, A. castellana, A. gigantea, A. pallens, and A. sp. These data will be available to USDA-APHIS for use in creating a risk assessment model for commercial transgenic grass seed production." |
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