Skip to main content

Physiological Mechanisms of Glyphosate Resistance

  • Wendy Pline-Srnic (a1)

Glyphosate, a nonselective herbicide and also the world's most widely used herbicide, inhibits 5-enol-pyruvylshikimate-3-phosphate synthase (EPSPS), an enzyme in the aromatic amino acid biosynthetic pathway. Because of its broad-spectrum and potent weed control and favorable environmental characteristics, attempts to engineer glyphosate resistance have been intensive in the past few decades. The use of at least three different mechanisms has conferred glyphosate resistance in normally sensitive crop species. Early work focused on progressive adaptation of cultured plant cells to stepwise increases in glyphosate concentrations. The resulting cells were resistant to glyphosate because of EPSPS overexpression, EPSPS gene amplification, or increased enzyme stability. Further work aimed to achieve resistance by transforming plants with glyphosate metabolism genes. An enzyme from a soil microorganism, glyphosate oxidoreductase (GOX), cleaves the nitrogen– carbon bond in glyphosate yielding aminomethylphosphonic acid. Another metabolism gene, glyphosate N-acetyl transferase (gat), acetylates and deactivates glyphosate. A third mechanism, and the one found in all currently commercial glyphosate-resistant crops, is the insertion of a glyphosate-resistant form of the EPSPS enzyme. Several researchers have used site-directed mutagenesis or amino acid substitutions of EPSPS. However, the most glyphosate-resistant EPSPS enzyme to date has been isolated from Agrobacterium spp. strain CP4 and gives high levels of resistance in planta. Weeds resistant to glyphosate have offered further physiological mechanisms for glyphosate resistance. Resistant field bindweed had higher levels of 3-deoxy-d-arbino-heptulosonate 7-phosphate synthase, the first enzyme in the shikimate pathway, suggesting that increased carbon flow through the shikimate pathway can provide glyphosate resistance. Resistant goosegrass has reduced translocation of glyphosate out of the treated area. Although glyphosate resistance has been achieved by numerous mechanisms, currently the only independent physiological mechanism to give adequate and stable resistance to glyphosate for commercialization of glyphosate-resistant crops has been glyphosate-resistant forms of EPSPS.

Corresponding author
Corresponding author's E-mail:
Hide All
Amrhein, N., Johanning, D., Schab, J., and Schulz, A. 1983. Biochemical basis for glyphosate tolerance in a bacterium and a plant tissue culture. FEBS Lett. 157:191196.
Anonymous. 2003a. January 16. Summary Information Format. Roundup Ready Sugar Beet. According to Council Regulation 2002/812/EC: Web page: Accessed: January 23, 2004.
Anonymous. 2003b. June 30. Acreage-Biotechnology Varieties. National Agricultural Statistics Service, Cr. Pr. 2–5: Web page: Accessed: January 21, 2004.
Baerson, S. R., Rodriguez, D. J., Tran, M., Feng, Y., Best, N. A., and Dill, G. M. 2002. Glyphosate resistant goosegrass. Identification of a mutation in the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase. Plant Physiol. 129:12651275.
Barry, G., Kishore, G., Padgette, M., Kolacz, K., Weldon, M., Re, D., Eichholtz, D., Fincher, K., and Hallas, L. 1992. Inhibitors of amino acid biosynthesis: strategies for imparting glyphosate tolerance to crop plants. in Singh, B. K., Flores, H. E., and Shannon, J. C., eds. Biosynthesis and Molecular Regulation of Amino Acids in Plants. Rockville, MD: American Society of Plant Physiologists. Pp. 139145.
Bradshaw, L. D., Padgette, S. R., Kimball, S. L., and Wells, B. H. 1997. Perspectives on glyphosate resistance. Weed Technol. 11:189198.
Castle, L. A., Siehl, D., Giver, L. J., Minshull, J., Ivy, C., Chen, Y. H., and Duck, N. B. inventors; Maxygen, Inc. and Pioneer Hi-Bred International, Inc., assignees. 2002. Novel glyphosate N-acetyltransferase (GAT) genes. WO 02/36782. May 10, 2002.
Castle, L. A., Siehl, D. L., and Gorton, R. et al. 2004. Discovery and directed evolution of a glyphosate tolerance gene. Science 304:11511154.
Comai, L., Sen, L., and Stalker, D. M. 1983. An altered aroA gene product confers resistance to the herbicide glyphosate. Science 221:370371.
Comai, L., Facciotti, D. D., Hiatt, W. R., Thompson, G., Rose, R. E., and Stalker, D. M. 1985. Expression in plants of a mutant aroA gene from Salmonella typhimurium confers tolerance to glyphosate. Nature 317:741744.
Cresswell, R. C., Fowler, M. W., and Scragg, A. H. 1988. Glyphosate tolerance in Catharanthus roseus . Plant Sci. 54:5563.
Dams, T. R., Anderson, P. C., Daines, R. J., Gordon-Kamm, W. J., Kausch, A. P., Mackey, C. J., Orozco, E. M., Orr, P. M., and Stephens, M. A. inventors; Dekalb Genetics Corporation, assignee. 1995. Fertile, transgenic maize plants and methods for their production. World patent WO 95/06128. March 2, 1995.
Delannay, X., Bauman, T. T., and Beighley, D. H. et al. 1995. Yield evaluation of a glyphosate-tolerant soybean line after treatment with glyphosate. Crop Sci. 35:14611467.
Dröge, W., Bröer, I., and Puhler, A. 1992. Transgenic plants containing the phosphinothricin-N-acetyltransferase gene metabolize the herbicide L-phosphinothricin (glufosinate) differently from untransformed plants. Planta 187:142151.
Duke, S. O., Rimando, A. M., Pace, P. F., Reddy, K. N., and Smeda, R. J. 2003. Isoflavone, glyphosate, and aminomethylphosphonic acid levels in seeds of glyphosate-treated, glyphosate-resistant soybean. J. Agric. Food Chem. 51:340344.
Dyer, W. E., Weller, S. C., Bressan, R. A., and Herrmann, K. M. 1988. Glyphosate tolerance in tobacco (Nicotiana tabacum L). Plant Physiol. 88:661666.
Elmore, R. W., Roeth, F. W., Klein, R. N., Knezevic, S. Z., Martin, A., Nelson, L. A., and Shapiro, C. A. 2001. Glyphosate-resistant soybean cultivar response to glyphosate. Agron. J. 93:404407.
Fillatti, J. J., Kiser, J., Rose, R., and Comai, L. 1987. Efficient transfer of a glyphosate tolerance gene into tomato using a binary Agrobacterium tumefaciens vector. Biotechnology 5:726730.
Forlani, G., Nielsen, B., and Racchi, M. L. 1992. A glyphosate-resistant 5-enol-pyruvyl-shikimate-3-phosphate synthase confers tolerance to a maize cell line. Plant Sci. 85:915.
Franz, J. E., Mao, M. K., and Sikorski, J. A. 1997. Uptake, transport and metabolism of glyphosate in plants. in Franz, J. E., Mao, M. K., and Sikorski, J. A., eds. Glyphosate: A Unique Global Herbicide. ACS Monogr 189:143181.
Gasser, C. S., Winter, J. A., Hironaka, C. M., and Shah, D. M. 1988. Structure, expression, and evolution of the 5-enolpyruvylshikimate-3-phosphate synthase genes of petunia and tomato. J. Biol. Chem. 263:42804289.
Geiger, D. R. and Bestman, H. D. 1990. Self-limitation of herbicide mobility by phytotoxic action. Weed Sci. 38:324329.
Goldsbrough, P. B., Hatch, E. M., Huang, B., Kosinsky, W. G., Dyer, W. E., Herrmann, K. M., and Weller, S. C. 1990. Gene amplification in glyphosate tolerant tobacco cells. Plant Sci. 72:5362.
Gorlach, J., Schmid, J., and Amrhein, N. 1994. Abundance of transcripts specific for genes encoding enzymes of the prechorismate pathway in different organs of tomato (Lycopersion esculentum L.) plants. Planta 193:216223.
Gougler, J. A. and Geiger, D. R. 1981. Uptake and distribution of N-phosphonomethylglycine in sugarbeet plants. Plant Physiol. 68:668672.
Gower, S. A., Loux, M. M., Cardina, J., and Harrison, S. K. 2002. Effect of planting date, residual herbicide, and postemergence application timing on weed control and grain yield in glyphosate-tolerant corn (Zea mays). Weed Technol. 16:488494.
Gower, S. A., Loux, M. M., and Cardina, J. et al. 2003. Effect of postemergence glyphosate application timing on weed control and grain yield in glyphosate-resistant corn: results of a 2-yr multistate study. Weed Technol. 17:821828.
Hauptman, P. M., della-Cioppa, G., Smith, A. G., Kishore, G. M., and Widholm, J. M. 1988. Expression of glyphosate resistance in carrot somatic hybrid cells through the transfer of an amplified 5-enolpyruvylshikimate-3-phosphate synthase gene. Mol. Gen. Genet. 211:357363.
He, M., Nie, Y. F., and Xu, P. 2003. A T42M substitution in bacterial 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) generates enzymes with increased resistance to glyphosate. Biosci. Biotechnol. Biochem. 67:14051409.
He, M., Yang, Z. Y., Nie, Y. F., Wang, J., and Xu, P. 2001. A new type of class I bacterial 5-enopyruvylshikimate-3-phosphate synthase mutants with enhanced tolerance to glyphosate. Biochim. Biophys. Acta. 1568:16.
Hoagland, R. E. 1980. Effects of glyphosate on metabolism of phenolic compounds: VI. Effects of glyphosine and glyphosate metabolites on phenylalanine ammonia-lyase activity, growth, and protein, chlorophyll, and anthocyanin levels in soybean (Glycine max) seedlings. Weed Sci. 28:393400.
Holländer-Czytko, H., Johanning, D., Meyer, H. E., and Amrhein, N. 1988. Molecular basis for the overproduction of 5-enolpyruvylshikimate-3-phosphate synthase in a glyphosate-tolerant cell suspension culture of Corydalis sempervirens . Plant Mol. Biol. 11:215220.
Holländer-Czytko, H., Sommer, I., and Amrhein, N. 1992. Glyphosate tolerance of cultured Corydalis sempervirens cells is acquired by an increased rate of transcription of 5-enolpyruvylshikimate 3-phosphate synthase as well as a reduced turnover of the enzyme. Plant Mol. Biol. 20:10291036.
Jones, M. A. and Snipes, C. E. 1999. Tolerance of transgenic cotton to topical application of glyphosate. J. Cotton Sci. 3:1926.
Kishore, G. M., Brundage, L., Kolk, K., Padgette, S. R., Rochester, D., Huynh, K., and della-Cioppa, G. 1986. Isolation, purification and characterization of a glyphosate tolerant mutant E. coli EPSP synthase. Fed. Proc. 45:1506.
Kishore, G. M. and Jacob, G. S. 1987. Degradation of glyphosate by Pseudomonas sp. PG2982 via a sarcosine intermediate. J. Biol. Chem. 262:1216412168.
Klee, H. J., Muskopf, Y. M., and Gasser, C. S. 1987. Cloning of an Arabidopsis thaliana gene encoding 5-enolpyruvylshikimate-3-phosphate synthase: sequence analysis and manipulation to obtain glyphosate-tolerant plants. Mol. Gen. Genet. 210:437442.
Komossa, D., Gennity, I., and Sandermann, H. 1992. Plant metabolism of herbicides with C-P bonds: glyphosate. Pestic. Biochem. Physiol. 43:8594.
Lebrun, M., Sailland, A., and Freyssinet, G. inventors; Rhone-Poulenc Agrochimie, assignee. 1997. Mutated 5-enol pyruvylshikimate-3-phosphate synthase, gene coding for said protein and transformed plants containing said gene. World patent application WO9704103. February 6, 1997.
Lebrun, M., Sailland, A., Freyssinet, G., and Degryse, E. inventors; Bayer Crop Science S.A., assignee. 2003. Mutated 5-enolpyruvylshikimate-3-phosphate synthase, gene coding for said protein and transformed plants containing said gene. U.S. patent 6,566,587. May 20, 2003.
Light, G. G., Bauman, T. A., Dotray, P. A., Keeling, J. W., and Wester, D. B. 2003. Yield of glyphosate-tolerant cotton as affected by topical glyphosate applications on the Texas High Plains and Rolling Plains. J. Cotton Sci. 7:231235.
Malik, J., Barry, G., and Kishore, G. 1989. The herbicide glyphosate. Biofactors 2:1725.
Mannerlöf, M., Tuvesson, S., Steen, P., and Tenning, P. 1997. Transgenic sugar beet tolerant to glyphosate. Euphytica 94:8391.
McAllister, R. S. and Haderlie, L. C. 1985. Translocation of 14C-glyphosate and 14CO2-labeled photoassimilates in Canada thistle (Cirsium arvense). Weed Sci. 33:153159.
Moore, J. K., Braymer, H. D., and Larson, A. D. 1983. Isolation of a Pseudomonas sp. which utilizes the phosphonate herbicide glyphosate. Appl. Environ. Microbiol. 46:316320.
Murata, M., Ryu, J-H., Caretto, S., Rao, D., Song, H-S., and Widholm, J. M. 1998. Stability and culture limitations of gene amplification in glyphosate resistant carrot cell lines. J. Plant Physiol. 152:112117.
Nafziger, E. D., Widholm, J. M., Steinrucken, H. C., and Killmer, J. L. 1984. Selection and characterization of a carrot cell line tolerant to glyphosate. Plant Physiol. 76:571574.
Nap, J. P., Metz, P. L. J., Escaler, M., and Conner, A. J. 2003. The release of genetically modified crops into the environment. Part I. Overview of current status and regulations. Plant J. 33:118.
Nida, D. L., Kolacz, K. H., and Buehler, R. E. et al. 1996. Glyphosate-tolerant cotton: genetic characterization and protein expression. J. Agric. Food Chem. 44:19601966.
Odell, J. T., Nagy, F., and Chua, N-H. 1985. Identification of DNA sequences required for activity of the Cauliflower Mosaic Virus 35S promoter. Nature 313:810812.
Padgette, S. R., Kolacz, K. H., and Delannay, X. et al. 1995. Development, identification, and characterization of a glyphosate-tolerant soybean line. Crop Sci. 35:14511461.
Padgette, S. R., Re, D. B., Barry, G. F., Eichholtz, D. E., Delannay, X., Fuchs, R. L., Kishore, G. M., and Fraley, R. T. 1996. New weed control opportunities: development of soybeans with a Roundup Ready gene. in Duke, S. O., ed. Herbicide-Resistant Crops: Agricultural, Economic, Environmental, Regulatory, and Technological Aspects. Boca Raton, FL: CRC. Pp. 5384.
Padgette, S. R., Re, D. B., and Gasser, C. S. et al. 1991. Site-directed mutagenesis of a conserved region of the 5-enolpyruvylshikimate-3-phosphate synthase active site. J. Biol. Chem. 266:2236422369.
Papanikou, E., Brotherton, J. E., and Widholm, J. M. 2004. Length of time in tissue culture can affect the selected glyphosate resistance mechanism. Planta 218:589598.
Pline, W. A., Price, A. J., Wilcut, J. W., Edmisten, K. L., and Wells, R. 2001. Absorption and translocation of glyphosate in glyphosate-resistant cotton as influenced by application method and growth stage. Weed Sci. 49:460467.
Pline, W. A., Viator, R., Wilcut, J. W., Edmisten, K. L., Thomas, J., and Wells, R. 2002. Reproductive abnormalities in glyphosate-resistant cotton caused by lower CP4-EPSPS levels in the male reproductive tissue. Weed Sci. 50:438447.
Reddy, K. N., Rimando, A. M., and Duke, S. O. 2004. Is aminomethylphosphonic acid, a metabolite of glyphosate, causing injury in glyphosate-treated glyphosate-resistant soybean? WSSA Abstr. 44:116.
Reinbothe, S., Nelles, A., and Partbier, B. 1991. N-(phosphonomethyl)glycine (glyphosate) tolerance in Euglena gracilis acquired by either overproduced or resistant 5-enolpyruvyl shikimate-3-phosphate synthase. Eur. J. Biochem. 198:365373.
Rubin, J. L., Gaines, C. G., and Jensen, R. A. 1984. Glyphosate inhibition of 5-enolpyruvylshikimate 3-phosphate synthase from suspension-cultured cells of Nicotiana silvestris . Plant Physiol. 75:839845.
Rueppel, M. L., Brightwell, B. B., Schaefer, J., and Marvel, J. T. 1977. Metabolism and degradation of glyphosate in soil and water. J. Agric. Food Chem. 25:517528.
Ruff, T., Eichholtz, D., Re, D., Padgette, S., and Kishore, G. 1991. Effects of amino acid substitutions on glyphosate tolerance and activity of EPSPS. Plant Physiol. 96: (Suppl.). 94.
Sandberg, C. L., Meggitt, W. F., and Penner, D. 1980. Absorption, translocation and metabolism of 14C-glyphosate in several weed species. Weed Res. 20:195200.
Sellin, C., Forlani, G., Dubois, J., Nielsen, E., and Vasseur, J. 1992. Glyphosate tolerance in Cichorium intybus L. var. Magdebourg. Plant Sci. 85:223231.
Shah, D. M., Horsch, R. B., and Klee, H. J. et al. 1986. Engineering herbicide tolerance in transgenic plants. Science 233:478481.
Shyr, Y. Y. J., Hepburn, A. G., and Widholm, J. M. 1992. Glyphosate selected amplification of the 5-enolpyruvylshikimate-3-phosphate synthase gene in cultured carrot cells. Mol. Gen. Genet. 232:377382.
Singer, S. R. and McDaniel, C. N. 1985. Selection of glyphosate-tolerant tobacco calli and the expression of this tolerance in regenerated plants. Plant Physiol. 78:411416.
Smart, C. C., Johanning, D., Muller, G., and Amrhein, N. 1985. Selective overproduction of 5-enol-pyruvylshikimic acid 3-phosphate synthase in a plant cell culture which tolerates high doses of the herbicide glyphosate. J. Biol. Chem. 260:1633816346.
Smith, C. M., Pratt, D., and Thompson, G. A. 1986. Increased 5-enolpyruvylshikimic acid 3-phosphate synthase activity in a glyphosate-tolerant variant strain of tomato cells. Plant Cell Rep. 5:298301.
Sost, D. and Amrhein, N. 1990. Substitution of Gly-96 to Ala in the 5-enolpyruvylshikimate-3-phosphate synthase of Klebsiella pneumoniae results in a greatly reduced affinity for the herbicide glyphosate. Arch. Biochem. Biophys 282:433436.
Sost, D., Schulz, A., and Amrhein, N. 1984. Characterization of a glyphosate-insensitive 5-enolpyruvyl-shikimic acid-3-phosphate synthase. FEBS Lett. 173:238242.
Stalker, D. M., Hiatt, W. R., and Comai, L. 1985. A single amino acid substitution in the enzyme 5-enolpyruvylshikimate-3-phosphate synthase confers resistance to the herbicide glyphosate. J. Biol. Chem. 260:47244728.
Steinrucken, H. C., Schulz, A., Amrhein, N., Porter, C. A., and Fraley, R. T. 1986. Overproduction of 5-enolpyruvyl-shikimate 3-phosphate synthase in a glyphosate-tolerant Petunia hybrida cell line. Arch. Biochem. Biophys 244:169178.
Suh, H., Hepburn, A. G., Kriz, A. L., and Widholm, J. M. 1993. Structure of the amplified 5-enolpyruvylshikimate-3-phosphate synthase gene in glyphosate resistant carrot cells. Plant Mol. Biol. 22:195205.
Tharp, B. E. and Kells, J. J. 1999. Influence of herbicide application rate, timing, and interrow cultivation on weed control and corn (Zea mays) yield in glufosinate-resistant and glyphosate-resistant corn. Weed Technol. 13:807813.
Thompson, C. J., Movva, R. N., Tizard, R., Crameri, R., Davies, J. E., Lauwereys, M., and Botterman, J. 1987a. Characterization of the herbicide-resistance gene bar from Streptomyces hygroscopicus . EMBO J. 9:25192523.
Thompson, G. A., Hiatt, W. R., Gacciotti, D., Stalker, D. M., and Comai, L. 1987b. Expression in plants of a bacterial gene coding for glyphosate resistance. Weed Sci. 35: (Suppl. 1). 1923.
Torstensson, L. 1985. Behavior of glyphosate in soils and its degradation. in Grossbard, E. and Atkinson, D., eds. The Herbicide Glyphosate. London: Butterworth. Pp. 137150.
Torstensson, N. T. L. and Aamisepp, A. 1977. Detoxification of glyphosate in soil. Weed Res. 17:209212.
Wang, H. Y., Li, Y. F., Xie, L. X., and Xu, P. 2003. Expression of a bacterial aroA mutant, aroA-M1, encoding 5-enolpyruvylshikimate-3-phosphate synthase for the production of glyphosate-resistant tobacco plants. J. Plant Res. 116:455460.
Wang, Y. X., Jones, J. D., Weller, S. C., and Goldsbrough, P. B. 1991. Expression and stability of amplified genes encoding 5-enolpyruvylshikimate-3-phosphate synthase in glyphosate-tolerant tobacco cells. Plant Mol Biol. 17:11271138.
Warner, S. A. J., Hawkes, T. R., and Andrews, C. J. inventors; Syngenta Limited, assignee. 2002. Herbicide Resistant Plants. WO 02/26995. April 4, 2002.
Weaver, L. M. and Herrmann, K. M. 1997. Dynamics of the shikimate pathway in plants. Trends Plant Sci. 2:346351.
Westwood, J. H. and Weller, S. C. 1997. Cellular mechanisms influence differential glyphosate sensitivity in field bindweed (Convolvulus arvensis) biotypes. Weed Sci. 45:211.
Widholm, J. M., Chinnala, A. R., Ryu, J., Song, H., Eggetta, T., and Brothertona, J. E. 2001. Glyphosate selection of gene amplification in suspension cultures of 3 plant species. Physiol. Plant. 112:540545.
Wyrill, J. B. and Burnside, O. C. 1976. Absorption, translocation, and metabolism of 2,4-D and glyphosate in common milkweed and hemp dogbane. Weed Sci. 24:557566.
Zhou, H., Arrowsmith, J. W., and Fromm, M. E. et al. 1995. Glyphosate-tolerant CP4 and GOX genes as a selectable marker in wheat transformation. Plant Cell Rep. 15:159163.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Weed Technology
  • ISSN: 0890-037X
  • EISSN: 1550-2740
  • URL: /core/journals/weed-technology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed