Poster: Emerging Technologies
Abs #
890: Genetic engineering of plants for high-level resistance to the herbicide, dicamba
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Presenter: |
Weeks, Don , dweeks1@unl.edu |
Authors | Weeks, Don (A) Chakraborty, Sarbani (A) Behrens, Mark (A) Herman, Pat (A) Arendsen, Sander (A) Clemente, Tom (A) | | Affiliations: |
(A): University of Nebraska-Lincoln
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Dicamba has been used as an environment-friendly herbicide for the control of broadleaf weeds in corn and wheat crops since 1965. To allow the potential use of dicamba for the control of weeds in broadleaf crops such as soybeans, cotton, canola, and certain vegetables, we have explored the possibility of genetically engineering plants to produce one or more heterologous enzymes capable of inactivating dicamba in plant cells before it builds to toxic levels. This goal has been accomplished using the oxygenaseDIC gene from Pseudomonas maltophilia, strain DI-6. When this gene is placed under the control of a strong, constitutive plant virus promoter and inserted via Agrobacterium-mediated plant transformation into tobacco and tomato plants, complete resistance to treatment with dicamba at concentrations of 25 lb/A and greater has been achieved. This level of dicamba compares with the 0.25-0.5 lb/A used for weed control in corn and wheat fields. Given that distinct herbicidal symptoms can be observed in wild-type tobacco and tomato plants at 0.001 lb/A dicamba, the results represent a decrease in herbicide sensitivity of at least 25,000 fold in plants genetically engineered with the dicamba resistance gene. The oxygenaseDIC along with two other components, reductaseDIC and ferredoxinDIC, constitute a small electron transport chain that catalyses to O-demethylation of dicamba and results in the formation of 3,6-dichlorosalicylate, a compound lacking herbicidal activity. All three genes have been cloned and genetically engineered for expression in plants. However, only the oxygenaseDIC component is required for herbicidal inactivation in transgenic plants and functions either in the cytoplasm or chloroplast compartments of the cell.
