Expression of Bt cry1Ac in transgenic oilseed rape in China and transgenic performance of intraspecific hybrids against Helicoverpa armigera larvae |
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Authors: | Yin-Ting Le CN Stewart Jr Hong Shi Wei Wei Xiang-Cheng Mi & Ke-Ping Ma |
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Affiliation: | Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Science, Beijing, China; Graduate University of Chinese Academy of Sciences, Beijing, China; Department of Plant Sciences, University of Tennessee, Knoxville, TN, USA; College of Plant Protection, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China |
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Abstract: | The expression of a synthetic Bacillus thuringiensis ( Bt ) cry1Ac gene in oilseed rape (OSR, Brassica napus ) was monitored under field conditions in China, and performance against Helicoverpa armigera larvae was compared in intraspecific hybrids with a Chinese OSR variety. Leaf samples from transgenic OSR were collected at various developmental stages in two separate field experiments. The Bt Cry1Ac concentrations in the third uppermost leaves increased before pod formation stage and either increased or decreased after pod formation stage whereas the total soluble protein increased before and decreased after pod-fill in the later growing season. Spontaneously formed intraspecific hybrids between transgenic OSR and a Chinese conventional OSR were obtained in the field and transgenic status was confirmed by a green fluorescent protein (GFP) phenotype and polymerase chain reaction. A bioassay on the neonate larvae of a susceptible strain of H. armigera was performed to test the efficacy of Bt Cry1Ac toxin in hybrid OSR plants. Both the original transgenic OSR and hybrid plants had a negative effect on body-weight gain of insect larvae. It was assumed that Bt Cry1Ac toxin concentration was similar in hybrids compared to the original transgenic OSR at the investigated developmental stages. The frequency of hybrid production and volunteerism could potentially enhance the evolution of insect pest tolerance in the field. |
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Keywords: | Brassica napus'Westar' hybridisation risk assessment total soluble protein winter oilseed rape area |
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