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MATERNAL EFFECTS IN ADVANCED HYBRIDS OF GENETICALLY MODIFIED AND NON-GENETICALLY MODIFIED BRASSICA SPECIES
BAUTISTA, N. S., C. L. SAGER, AND L. S. WATRUD. MATERNAL EFFECTS IN ADVANCED HYBRIDS OF GENETICALLY MODIFIED AND NON-GENETICALLY MODIFIED BRASSICA SPECIES. Presented at Joint Annual Meeting of American Society of Plant Biologists & the Canadian Society of Plant Physiologists, Boston, MA, August 05 - 09, 2006.
Identification of fitness traits potentially impacted by gene flow from genetically modified (GM) crops to compatible relatives is of interest in risk assessments for GM crops. Reciprocal crosses were made between GM canola, Brassica napus cv. RaideRR that expresses CP4 EPSPS for resistance to glyphosate herbicide, and its commercial and weedy relatives, non-GM B. napus (Sponsor, Defender, Westar and GRIN 41) and bird¿s rape mustard, B. rapa, (GRIN 42 and 43). We evaluated the effects of parental and maternal genotypes on two fitness-related traits, flowering phenology and seed mass, among F1 and later generation hybrids (F2, BC1). All F1 progeny had the CP4 EPSPS gene and the segregation ratio of 88:29 in the F2 generation fit the expected 3:1 segregation for a dominant trait. Among parental lines, days to flowering (FT) of the weedy B. rapa lines (GRIN 42 and 43) were significantly different from each other, and significantly reduced relative to the four commercial B. napus lines. Maternal effects were apparent in all hybrids, but were most pronounced among F1 progeny of the interspecific crosses. Further, hybrid generations differed significantly in seed mass, but overall, seed mass was substantially less in later hybrid generations (F2, BC1) than in the F1. These results indicate that mating history, and both maternal and backcross effects influence the distribution of important fitness-related traits that may determine the persistence of transgenes outside of cultivation.