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EXTENDED FERTILITY AND COMPATIBILITY OF PROGENY WITHINT HE AGROSTIS HYBRIDIZING COMPLEX: IMPLICATIONS FOR TRANSGENE ESCAPE AND PERSISTENCE WITHIN WILD POPULATION
Citation:
REICHMAN, J. R., M. A. BOLLMAN, G. KING, AND L. S. WATRUD. EXTENDED FERTILITY AND COMPATIBILITY OF PROGENY WITHINT HE AGROSTIS HYBRIDIZING COMPLEX: IMPLICATIONS FOR TRANSGENE ESCAPE AND PERSISTENCE WITHIN WILD POPULATION. Presented at Botany & Plant Biology 2007 Joint Congress, Chicago, IL, July 07 - 11, 2007.
Description:
Agrostis stolonifera L. (creeping bentgrass) is a turf grass that is of interest for introduction of herbicide and disease resistance, and stress tolerance traits by genetic engineering. A. stolonifera is a member of a hybridizing complex that includes at least eleven Agrostis species and two Polypogon species with broad overlapping geographic distributions in North America. Thus, there is high potential for transgene flow among the compatible species, but the full extent of hybridizing linkages within the complex is not known. We previously demonstrated transgene escape from genetically engineered (GE) bentgrass field test sites into naturalized Agrostis populations in Oregon, USA. The ecological fate and effects of the escapes are undetermined as of yet. Nevertheless, the persistence of selectively advantageous or neutral transgenes can be predicted in populations where fertile F1 hybrid progeny form. In this study, we conducted a comprehensive greenhouse screening of non-transgenic Agrostis species known to occur in the Pacific Northwest to identify hybrids that can successfully backcross to parent species, self fertilize, and/or further outcross to other species. Several previously un-reported hybridization pathways were identified, including successful inter-specific crosses between the obligate out-crossing A. stolonifera and A. exarata, a common, self-fertile, native species. The ecological implications of this cross include potential movement of engineered genes into native genomes, and increased weediness of GE entities resulting from possible self-compatibility and likely increase in the ability of hybrids to exploit new niches through broadened environmental tolerances relative to the parents. The results from these crosses provide valuable information on: 1) individual Agrostis spp. hybridization success, 2) inter-relationships among the various species used, and 3) potential ecological effects of transgene flow within the genus through delineation of flow pathways. This information will be critical for a thorough risk assessment of potential ecological effects of transgene flow in Agrostis.