DOW JONES NEWSWIRES 
 

Monsanto Co. (MON) said Tuesday it filed a patent-infringement lawsuit Monday in federal court against DuPont Co. (DD) and unit Pioneer Hi-Bred International Inc. to prevent what the world's largest seed supplier alleges is the illegal use of its Roundup Ready herbicide-tolerant technologies.

Pioneer has the right to sell soybeans and corn with the Roundup Ready trait. Pioneer has publicly said for several years it would replace the trait with DuPont's Optimum GAT trait, but it recently said the Optimum GAT trait when used alone poses unacceptable risks to farmers, according to Monsanto.

Monsanto alleges Pioneer is using its Roundup Ready trait to mask problems with the other trait, violating its contract rights and patents.

The two companies have met in court before over patents - a court determined years ago that Pioneer breached its license and improperly used Monsanto's YieldGard corn borer trait. Both companies were also been named in similar lawsuits by Syngenta AG (SYT) in 2002.

DuPont had no immediate comment.

Monsanto's shares were recently down 0.6% at $88.45 in premarket trading and DuPont's were down 0.5% at $29.26.

-By Kerry E. Grace, Dow Jones Newswires; 201-938-5089; kerry.grace@dowjones.com