Novel synthetic Bacillus thuringiensiscry1B gene and the cry1B-cry1Ab translational fusion confer resistance to southwestern corn borer, sugarcane borer and fall armyworm in transgenic tropical maize |
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Authors: | N Bohorova R Frutos M Royer P Estañol M Pacheco Q Rascón S McLean D Hoisington |
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Institution: | (1) CIMMYT, Apdo. Postal 6-641, 06600 Mexico, D. F., Mexico e-mail: d.hoisington@cgiar.org Tel.: +52-5804-7575, Fax: +52-5804-7567, Present address: N. Bohorova, Research Director, Epicyte Pharmaceutical Inc., 5810 Nancy Ridge Drive, Suite 150, San Diego, CA 92121, USA, MX;(2) CIRAD, TA 40/02, 34398 Montpellier, cedex 5, France, FR |
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Abstract: | In order to develop a resistance management strategy to control tropical pests based on the co-expression of different toxins,
a fully modified Bacillus thuringiensis
cry1B gene and the translational fusion cry1B-cry1Ab gene have been developed. Both constructs were cloned under the control of a maize ubiquitin-1 or a rice actin-1 promoter
and linked to the bar gene driven by the CaMV 35S promoter. Immature embryos from the tropical lines CML72, CML216, and their hybrids, were used
as the target for transformation by microprojectile bombardment. Twenty five percent of the transformed maize plants with
cry1B expressed a protein that is active against southwestern corn borer and sugarcane borer. Ten percent of the transgenic maize
expressed single fusion proteins from the translational fusion gene cry1B-1Ab and showed resistance to these two pests as well as to the fall armyworm. Transgenic maize plants that carried the cry1B gene in T1 to T3 progenies transmitted trangenes with expected Mendelian segregation and conferred resistance to the two
target insects. Molecular analyses confirmed the cry genes integration, the copy number, the size of protein(s) expressed in maize plants, the transmission, and the inheritance
of the introduced cry gene. These new transgenic products will provide another recourse for reducing the build-up of resistance in pest populations.
Received: 25 September 2000 / Accepted: 15 December 2000 |
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Keywords: | Tropical maize Transformation Plant regeneration Insect resistance Bacillus thuringiensis (Bt) |
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