A patent issued today to Pioneer Hi-Bred International, Inc. gives the company broad claims to a method for making transgenic corn.

US Patent 5,990,387 covers one process researchers can use to genetically enhance corn plants, which enables them to introduce a wide variety of traits that offer value to farmers, consumers and the environment.

"This patent is a reflection of the original research being done at Pioneer and is a tribute to the
talented people working here,'' said Herb Jervis, Pioneer vice president and chief intellectual
property counsel.

"The breadth of the claims issued today is consistent with the Patent Office's long-standing
policy of granting a broader claim scope to earlier innovators than those who filed later in the
same field,'' said Jervis.

Pioneer developed the system for corn transformation using the "gene gun'' technology. But
rights to products derived from bombardment-mediated transformation -- including insect and
herbicide resistant hybrids and inbreds on the market today -- are in dispute.

DeKalb Genetics sued Pioneer and others over a series of narrower patents DeKalb was
granted in 1996. Since then, one of the DeKalb suits has been stayed and two others against
Pioneer have been dismissed with prejudice.

As was the case with a patent issued to Pioneer in March of this year, this patent's early filing
date shows Pioneer's early entry into corn transformation using microparticle bombardment. The
application that gave rise to both patents was filed in June 1988 -- more than 18 months before
others applied for patents relating to microparticle bombardment-mediated plant transformation.

Pioneer Hi-Bred International, Inc., a DuPont business, is the world's leading developer and
supplier of advanced plant genetics to farmers. With headquarters in Des Moines, Iowa, Pioneer
develops, produces and markets a full line of top-quality seeds, forage and grain additives and
provides services to customers in nearly 100 countries.

DuPont is a science company, delivering science-based solutions that make a difference in people's lives in food and nutrition; health care; apparel; home and construction; electronics; and transportation.

Company news release
N2260