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United States Department of Agriculture

Agricultural Research Service

Research Project: WEED BIOLOGY AND ECOLOGY, AND DEVELOPMENT OF SUSTAINABLE INTEGRATED WEED MANAGEMENT SYSTEMS FOR COTTON, SOYBEAN, CORN Title: Aminomethylphosphonic acid accumulation in plant species treated with glyphosate

Authors
item Reddy, Krishna
item Rimando, Agnes
item Duke, Stephen
item Nandula, Vijay - DREC - STONEVILLE, MS

Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 22, 2008
Publication Date: February 26, 2008
Citation: Reddy, K.N., Rimando, A.M., Duke, S.O., Nandula, V.K. 2008. Aminomethylphosphonic acid accumulation in plant species treated with glyphosate. Journal of Agriculture and Food Chemistry 56:2125-2130.

Interpretive Summary: Aminomethylphosphonic acid (AMPA) is produced from glyphosate degradation in glyphosate-resistant (GR) soybean treated with glyphosate, and has been shown to cause injury to plants. Scientists at USDA-ARS Southern Weed Science Research Unit, Stoneville, MS; USDA-ARS Natural Products Utilization Research Unit, Oxford, MS; and Delta Research and Extension Center, Stoneville, MS have investigated if other crops and weeds also produce AMPA following glyphosate treatment. Studies determined the glyphosate I50 values (rate required to cause a 50% reduction in plant growth) and measured AMPA concentrations in selected plant species treated with glyphosate at I50 rate. Coffee senna was the most sensitive and hemp sesbania was the most resistant to glyphosate. Hemp sesbania was six-fold and Illinois bundleflower was four-fold more resistant to glyphosate than coffee senna. AMPA was detected in six of the seven leguminous species studied, but not detected in corn, Italian ryegrass or velvet leaf. These results suggest that some leguminous species are more resistant to glyphosate than others, and certain plants possess an enzyme for breakdown of glyphosate to AMPA.

Technical Abstract: Aminomethylphosphonic acid (AMPA) is the most frequently detected metabolite of glyphosate in plants. Greenhouse studies were conducted to determine the glyphosate I50 values (rate required to cause a 50% reduction in plant growth) and to quantify AMPA and shikimate concentrations in selected leguminous and non-leguminous species treated with glyphosate at I50 rate. Coffee senna [Cassia occidentalis (L.) Link] was the most sensitive (I50, 75 g/ha) and hemp sesbania [Sesbania herbacea (P.Mill.) McVaugh] was the most resistant (I50, 456 g/ha) to glyphosate. Hemp sesbania was six-fold and Illinois bundleflower [Desmanthus illinoensis (Michx.) MacM. ex B.L.Robins. & Fern.] was four-fold more resistant to glyphosate than coffee senna. Glyphosate was present in all plant species and its concentration ranged from 0.308 to 26.8 'g/g of tissue. AMPA was present in all leguminous species except hemp sesbania. AMPA concentration ranged from 0.119 to 4.77 'g/g of tissue. AMPA was detected in six of the seven leguminous species studied. Shikimate was present in all plant species treated with glyphosate and levels ranged from 0.053 to 16.5 mg/g of tissue. Non-glyphosate-resistant (non-GR) soybean accumulated much higher shikimate than glyphosate-resistant (GR) soybean. These results suggest that some leguminous species are more resistant to glyphosate than others, and a plant glyphosate oxidoreductase (GOX) may be responsible for breakdown of glyphosate to AMPA.

Last Modified: 10/21/2014
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