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ARS Home » Northeast Area » Geneva, New York » Grape Genetics Research Unit (GGRU) » Research » Publications at this Location » Publication #310510
Title: Benefits of transgenic insect resistance in Brassica hybrids under selection

Author
item SAGERS, CYNTHIA - University Of Arkansas
item Londo, Jason
item BAUTISTA, NONNIE - Institute Of Biology - Brazil
item LEE, E - Environmental Protection Agency (EPA)
item KING, GEORGE - Environmental Protection Agency (EPA)
item WATRUD, LIDIA - Environmental Protection Agency (EPA)

Submitted to: Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2014
Publication Date: 1/8/2015
Citation: Sagers, C., Londo, J.P., Bautista, N., Lee, E.H., King, G., Watrud, L. 2015. Benefits of transgenic insect resistance in Brassica hybrids under selection. Journal of Agronomy. 5(1):21-34.

Interpretive Summary: Field trials of transgenic crops have occasionally resulted in unintentional escape of transgenes out of crop fields and into closely related species through transfer of pollen. Hybridization between transgenic cultivars and close relatives may create novel hybrid plant forms with potential negative ecological outcomes for wild and weedy plant populations if hybrid plants have increased competitiveness. We report here the outcome of studies with canola (Brassica napus), transgenic canola, a sexually compatible weed B. rapa, and their hybrids grown within contained mesocosm greenhouses. Brassica rapa was hybridized with non-transgenic canola and transgenic canola carrying a transgene for herbivore resistance (Bt Cry1Ac) and grown in outdoor mesocosms under varying conditions of competition and insect herbivory. Treatment effects differed significantly among genotypes. Hybrids were larger than all other genotypes, and produced more seeds than the B. rapa parent. Under conditions of heavy herbivory, plants carrying the transgenic resistance were larger and produced more seeds than non-transgenic plants. The rate of gene flow from transgenic canola to B. rapa varied between years (5–22%). These results confirm that canola-weed hybrids benefit from transgenic resistance and are aggressive competitors with congeneric crops and ruderals. Because crop and crop-weed hybrids are competitively superior, escapees may alter the ecologies of native plant communities.

Technical Abstract: Field trials of transgenic crops have occasionally resulted in unintentional transgene flow to closely related species. Hybridization between transgenic cultivars and close relatives may create novel forms with potential negative outcomes for wild and weedy plant populations. We report here the outcome of mesocosm studies with canola (Brassica napus), transgenic canola, a sexually compatible weed B. rapa, and their hybrids. Brassica rapa was hybridized with canola and canola carrying a transgene for herbivore resistance (Bt Cry1Ac) and grown in outdoor mesocosms under varying conditions of competition and insect herbivory. Treatment effects differed significantly among genotypes. Hybrids were larger than all other genotypes, and produced more seeds than the B. rapa parent. Under conditions of heavy herbivory, plants carrying the transgenic resistance were larger and produced more seeds than non-transgenic plants. The rate of gene flow from transgenic canola to B. rapa varied between years (5–22%). These results confirm that canola-weed hybrids benefit from transgenic resistance and are aggressive competitors with congeneric crops and ruderals. Because crop and crop-weed hybrids are competitively superior, escapees may alter the ecologies of native plant communities.