Biotech Updates

Development of Monsanto's Glyphosate-resistant Cotton

June 25, 2010

The broad-spectrum herbicide glyphosate blocks the activity of the endogenous plant 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), an enzyme catalyzing the pathway of various plant functions. Glyphosate resistance has been engineered in many crops by an EPSPS enzyme variant from Agrobacterium sp. strain CP4 that binds glyphosate less effectively.

The first glyphosate-resistant cotton event (MON1445) used this CP4 EPSPS and was commercially released by Monsanto in 1997. However, there was incomplete expression of CP4 EPSPS in male reproductive tissues. Thus, different promoters were used to generate complete expression of the cp4 epsps gene. Based on the eight-year testing, MON 88913 event exhibited outstanding vegetative and reproductive resistance to glyphosate. The event was also inherited over multiple generations and the insertion line is simple, requiring only minimal modification of the cotton genetic make-up. Therefore, it was commercially released by Monsanto in 2006 as Roundup Ready Flex Cotton.

Subscribers of Crop Science Journal may download the research article at