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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #273172
Title: Gene flow in commercial alfalfa fields and implications to isolation and seed certification

Author
item TEUBER, LARRY - University Of California
item MUELLER, SHANNON - University Of California - Cooperative Extension Service
item Hagler, James
item VAN DEYNEZ, ALLEN - University Of California

Submitted to: The Science of Gene Flow in Agriculture and its Role in Co-existence
Publication Type: Proceedings
Publication Acceptance Date: 9/6/2011
Publication Date: 9/7/2011
Citation: Teuber, L.R., Mueller, S., Hagler, J.R., Van Deynez, A. 2011. Gene flow in commercial alfalfa fields and implications to isolation and seed certification. The Science of Gene Flow in Agriculture and its Role in Co-existence. 46-48.

Interpretive Summary: not required for Symposium Proceedings

Technical Abstract: Alfalfa (Medicago sativa L.) is a perennial species with an out-crossing rate of between 67 and 77 percent. Pollen is primarily vectored by bees. An accurate understanding of the frequency with which foreign pollen results in viable seed set is critical to establishing appropriate mechanisms for isolation and maintenance of genetic purity. Studies were conducted to determine the frequency of pollen mediated gene flow under commercial seed production conditions with either honey bees (Apis mellifera) or a combination of honey bees and alfalfa leaf cutter bees (Megachile rotundata) as pollinators. A 318 acre commercial seed production field with the Roundup Ready (RR) trait conferring Roundup® herbicide tolerance was used as a pollen-marking tool. Study site/trap plots (1.8 acres) were established between 165 ft and 5 miles. Approximately 1.2 million seedlings were evaluated for the presence of the RR trait from these study sites during each of two production years. There was a logarithmic decrease in gene flow between 165 ft and 3 miles from the RR source field. Gene flow averaged 1.67% at 165 ft, 0.22 percent at 1 mile, and was not detectable at 5 miles. These results are being utilized by seed certification agencies to develop isolation distances, and mapping and stewardship programs to be employed during the production of seed for markets that are sensitive to the presence of transgenic traits.