Dominant bar gene patents

The first and most dominant patent family has been divided into three individual key patents in the United States. The three key patents cover:
a) the use of the bar gene in a plant cell (US 5561236);
b) a process for the production of a plant cell tolerant or resistant to glufosinate (PPT) or any compound containing the PPT moiety, by nuclear integration of a compound-specific acetyl transferase gene (US 5646024); and
c) a plant transformation vector carrying such a gene (US 5648477).

The other patent in this dominant family is European Patent 242236. These patents have extremely broad claims, particularly European Patent 242236 and the United States patent 5561236. A summary of the claims for these patents can be viewed below, and is followed by an analysis of the scope of the granted claims.

Bayer Crop Science portfolio
(original assignees Plant Genetic Systems NV and Biogen NV)


EP 242236 B2 21 Aug 1996 This patent has the broadest coverage with respect to the bar gene. Claims recite a process to inactivate a glutamine synthetase (GS) inhibitor by expression of a heterologous resistance gene in plants and plant cells. Other claims specify that the enzyme is a phosphinothricin acetyl transferase (PAT) from Streptomyces sp. The use of this gene to produce herbicide resistant plants is also claimed. In another claim, resistance is exploited to protect plants from fungal infection by treating plants with phosphinothricin, which is not only a herbicide but an antibiotic. (see note below).
US 5561236 1 Oct 1996 The broadest claim covers a plant cell (and by extension a plant) transformed with an acetyl transferase gene capable of inactivating a GS inhibitor. The dependent claims then proceed to define the enzyme as PAT with a defined sequence (isolated from Streptomyces sp).
NOTE: In the U.S., three patents are related to EP 242236 and to each other.