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GA21 is a variety of Roundup Ready corn made by Monsanto that was deregulated in the U.S. in 1997 and first commercialized in the U.S. as 1998 under the brand name "Roundup Ready Corn." Monsanto mostly phased out its use following the release of a newer Roundup Ready trait, NK603. In 2007, Syngenta won permission to use the trait in a lawsuit against Monsanto.[1] It has been genetically engineered to survive being sprayed with the herbicide glyphosate, the active ingredient in Monsanto's herbicide Roundup. Roundup Ready crops, and genetically modified organisms are controversial around the world.


On April 9, 1997, Monsanto/DeKalb Genetics Corporation submitted a petition to deregulate GA21 to the USDA Animal and Plant Health Inspection Service (APHIS). On August 3, 1997, the USDA published a notice in the Federal Register, soliciting public comments, which were due by October 14, 1997. The USDA conducted an environmental assessment (EA) under the National Environmental Policy Act (NEPA) and issued a "finding of no significant impact" (FONSI). GA21 was deregulated on November 18, 1997.

At the time of deregulation, the USDA wrote in the Federal Register:

"Corn line GA21 has been genetically engineered to contain a modified 5-enolpyruvyishikimate3-phosphate synthase (EPSPS) gene, which, when expressed in the plant, confers tolerance to the herbicide glyphosate. The modified corn EPSPS gene was introduced into the parental inbred corn line AT by the particle acceleration method, and its expression is controlled in part by the rice actin promoter and intro and the NOS 3' termination sequence derived from the plant pathogen Agrobacterium tumefaciens.[2]


Monsanto branded GA21 as Roundup Ready® Corn and introduced it in the U.S. in 1998.[3] It was the first variety of Roundup Ready (glyphosate tolerant) corn sold commercially. However, since 2001, Monsanto has mostly replaced GA21 with a new type of Roundup Ready corn (NK603), which it branded as "Roundup Ready 2."


Monsanto conducted a study of broiler chickens fed GA21 and MON 810 in 2003.[4]

Articles and resources

Related SourceWatch articles


  1. Touchdown Ready Maize - Maize GA21 (Syngenta), Accessed August 12, 2012.
  2. Federal Register, Vol 62, No 234, December 5, 1997.
  3. Monsanto Company History, Accessed August 12, 2012.
  4. M.L. Taylor, G.F. Hartnell, S.G. Riordan, M.A. Nemeth, K. Karunanandaa, B. George, and J.D. Astwood, "Comparison of Broiler Performance When Fed Diets Containing Grain from YieldGard (MON810), YieldGard x Roundup Ready (GA21), and Nontransgenic Control, or Commercial Corn," Poultry Science, 2003.

External resources

External articles