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Title: INTRA- AND INTERSPECIFIC POLLEN-MEDIATED GENE FLOW FROM AN APOMICTIC KENTUCKY BLUEGRASS (POA PRATENSIS L.) GENOTYPE UNDER CULTIVATED FIELD CONDITIONS USING A TRANSGENIC TRAIT AS A MARKER

Author
item JOHNSON, P - UTAH STATE UNIVERSITY
item Larson, Steven
item PATTERSON, J - UTAH STATE UNIVERSITY
item CATTANI, D - SCOTTS COMPANY,GERVAIS
item NELSON, E - SCOTTS CO., MARYSVILLE

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2006
Publication Date: 9/8/2006
Citation: Johnson, P.G., Larson, S.R., Patterson, J.T., Cattani, D.J., Nelson, E.K. 2006. Intra- and interspecific pollen-mediated gene flow from an apomictic kentucky bluegrass (poa pratensis l.) genotype under cultivated field conditions using a transgenic trait as a marker. Crop Science 46(5):1990-1997

Interpretive Summary: Kentucky bluegrass (Poa pratensis L.), one of the most commonly grown turfgrasses in temperature regions, is being developed with transgenic traits. The use of this technology raises risk assessment questions as P. pratensis is a perennial plant and naturally competitieve in many habitats. Moreover, P. pratensis is known to hybridize with other Poa species and also contains several different chromosome sets that were assimilated by hybridization of different ancestral species and some of which have likeness to other modern-day Poa species. Although asexual reproduction (apomixes) may reduce gene transfer, this natural phenomenon is not present in all Poa species or P. pratensis varieties. To further understand the potential environmental impact of a transgenic P. pratensis, we measured intra- and interspecific pollen-mediated gene flow in field conditions from P. pratensis to other Poa species. Seedlings from the receptor plants were screened for resistance to glyphosate (herbicide). Transgene presence and parental identity was verified in all putative hybrids using PCR and DNA fingerprinting. Hybrids were found with P. interior, P. palustris, P. pratensis x P. secunda, and three other P. pratensis entries, but did not occur with P. annua, P. trivialis, or P. compressa, among other species. Overall hybrid frequency was 0.048%. While apomixis in receptor plants and pollen competition likely reduced the number of hybrids, gene flow did occur, but at low frequency and over short distances.

Technical Abstract: Kentucky bluegrass (Poa pratensis L.), one of the most commony grown turfgrasses in temperate regions, is being developed with transgenic traits. The use of this technology raises risk assessment questions as P. pratensis is perennial, often apomictic, competitive in many habitats, and hybridizes with other Poa. To further understand the potential environmental impact of a transgenic P. pratensis, we measured intra- and interspecific pollen-mediated gene flow in field conditions from P. pratensis to other Poa. We used a wagon-wheel design with a glyphosate resistant P. pratensis as a pollen donor and pollen receptor plots located at 13m and 53m along six equally spaced vectors. Each receptor plot included accessions from 25 Poa species. Seedlings from the receptor plants were screened for resistance to glyphosate and potential hybrids verified with PCR and genomic fingerprinting. Hybrids were found with P. interior, P. palustris, P. pratensis x P. secunda, and three other P. pratensis entries, but did not occur with P. annua, P. trivialis, or P. compressa, among other species. Overall hybrid frequency was 0.048%. Because few hybrids were obtained and variability due to wind on pollen flow direction and pollen competition, we were not able to effectively model gene flow trends over direction and distance. While apomixis in receptor plants and pollen competition likely reduced the number of hybrids, gene flow did occur, but at low frequency and over short distances.