Robust crop resistance to broadleaf and grass herbicides provided by aryloxyalkanoate dioxygenase transgenes.

Publication: Proceedings of the National Academy of Sciences of the United States of America
Publication Date: 2010
Study Author(s): Wright, Terry R;Shan, Guomin;Walsh, Terence A;Lira, Justin M;Cui, Cory;Song, Ping;Zhuang, Meibao;Arnold, Nicole L;Lin, Gaofeng;Yau, Kerrm;Russell, Sean M;Cicchillo, Robert M;Peterson, Mark A;Simpson, David M;Zhou, Ning;Ponsamuel, Jayakumar;Zhang, Zhanyuan;
Institution: Research and Development, Dow AgroSciences LLC, Indianapolis, IN 46268, USA.
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Engineered Glyphosate resistance is the most widely adopted genetically modified trait in agriculture, gaining widespread acceptance by providing a simple robust weed control system. However, extensive and sustained use of glyphosate as a sole weed control mechanism has led to field selection for glyphosate-resistant weeds and has induced significant population shifts to weeds with inherent tolerance to Glyphosate. Additional weed control mechanisms that can complement glyphosate-resistant crops are, therefore, urgently needed. 2,4-dichlorophenoxyacetic acid (2,4-D) is an effective low-cost, broad-spectrum herbicide that controls many of the weeds developing resistance to glyphosate. We investigated the substrate preferences of bacterial aryloxyalkanoate dioxygenase Enzymes (AADs) that can effectively degrade 2,4-D and have found that some members of this class can act on other widely used herbicides in addition to their activity on 2,4-D. AAD-1 cleaves the aryloxyphenoxypropionate family of grass-active herbicides, and AAD-12 acts on pyridyloxyacetate auxin herbicides such as triclopyr and fluroxypyr. Maize plants transformed with an AAD-1 gene showed robust crop resistance to aryloxyphenoxypropionate herbicides over four generations and were also not injured by 2,4-D applications at any growth stage. Arabidopsis plants expressing AAD-12 were resistant to 2,4-D as well as triclopyr and fluroxypyr, and transgenic Soybean plants expressing AAD-12 maintained field resistance to 2,4-D over five generations. These results show that single AAD transgenes can provide simultaneous resistance to a broad repertoire of agronomically important classes of herbicides, including 2,4-D, with utility in both monocot and dicot crops. These transgenes can help preserve the productivity and environmental benefits of herbicide-resistant crops.
PMID: 21059954

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