TITLE	Expression of a Bacillus thuringiensis cry1C gene in plastid confers high insecticidal efficacy against tobacco cutworm - a Spodoptera insect
AUTHOR	Chi-Hui Lin Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan 402 Yen-Yu Chen Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan 402 Ching-Chou Tzeng Department of Biopesticide, Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Wufeng, Taichung, Taiwan 413 Hsin-Sheng Tsay Department of Agronomy, Taiwan Agricultural Research Institute, Wufeng, Taichung, Taiwan 413 Liang-Jwu Chen Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan 402
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ABSTRACT	We have demonstrated that the toxic domain of a wild-type Bacillus thuringiensis (Bt) cry1C gene could be expressed efficiently in the chloroplasts of transplastomic tobacco plants, resulting in high resistance to tobacco insects. A DNA fragment with the toxic domain of a wild-type Bt cry1C gene was constructed under the control of rbcL promoter and an E. coli thra terminator in a plasmid vector flanked by chloroplast sequences. This plasmid vector was then delivered into the chloroplast through biolistic bombardment technique. Plant transformants that possessed spectinomycin and streptomycin resistance were selected, and the integration of cry1C gene in these transformants was confirmed by PCR and Southern analyses. Results from PCR and Southern hybridization indicated that the truncated cry1C gene was integrated into the chloroplast genome as we expected through homologous recombination. High expression level of the integrated Bt cry1C gene in the chloroplasts was observed through Northern and Western hybridization assays. These transplastomic tobacco plants are highly toxic to the tobacco cutworm Spodoptera litura, causing a mortality rate of 76.9% to 100% after 72 h of feeding. The truncated Bt toxin is expressed in high levels in the chloroplast (about 1% of total proteins) and the plastid transgenes were known not to transmit through pollen. So that, this study will facilitate not only improvement in breeding for insect-resistant plants, but also the prevention of contamination of transgenes among crop plants.
KEYWORD	Bacillus thuringiensis; Chloroplast; cry1C gene; Insecticidal protein; Nicotiana tabaccum; Plastid transformation; Spodoptera lituar;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 44 Number 3 July 2003, page 199-210, 12 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China