Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/13/2004
Publication Date: 9/13/2004
Citation: Fischer, A.J., Cheetham, D.P., Laca, E.A., Mckenzie, K.S., Gealy, D.R. 2004. Outcrossing study between transgenic herbicide-resistant rice and non-transgenic rice in California [abstract]. In: Ferrero, A., Vidotto, F., editors. Proceedings of the Conference Chanllenges and Opportunities for Sustainable Rice-Based Production Systems. International Rice Conference, September 13-15, 2004, Turin, Italy. p. 407-408. Interpretive Summary:
Technical Abstract: The introduction and rapid development of GMOs (i.e.- genetically modified organisms) has resulted in the global use of transgenic crops. Escape of engineered genes from transgenic crops through pollen flow to similar cultivars or related weedy species raises environmental concerns and can jeopardize the commercialization of conventional California rice. Our objective was to evaluate the potential for gene flow from transgenic rice plants to conventional rice plants using herbicide-resistance marker genes that had been incorporated into the most widely grown California japonica cultivar, M-202. Of particular interest was the open-field assessment of pollen flow distances and outcrossing rates under natural environmental conditions (i.e.- predominant wind flow) that occur in the water-seeded system of California. Two types of field experiments were conducted during 2001 to 2003 by the University of California-Davis at the Rice Experiment Station (RES) in Biggs, California to assess gene flow from the transgenic rice lines 'Liberty-Link M-202' (glufosinate resistant) and 'Round-Up Ready M-202' (glyphosate resistant) to conventional 'M-202' rice. The layout of the field pollen flow consisted of a circular (4.6 m radius) central donor site of transgenic rice surrounded by an acceptor site (16.9 m radius) seeded with non-transgenic M-202. The second study evaluated the highest potential for natural outcrossing by conducting a 'forced' outcrossing study where transgenic and non-transgenic rice were grown in alternate rows of pots placed in the field subject to mechanical pollination. The forced pollination studies revealed outcrossing rates ranging from 0.071 to 0.272% in single replication, and 0.010 to 0.216% when averaged across the four replications. In the circular pollen flow experiments, the outcrossing rates in single replication ranged from 0.010 to 0.415%. Rates averaged over four replications were from 0.007 to 0.108%. Natural outcrossing from transgenic rice to non-transgenic rice was detected no further than 1.8-meters from the transgenic source. There was no positive correlation between the effect of predominant wind flow and the extent of outcrossing from transgenic rice to non-transgenic rice.