Family 3. Selectable marker for development of vectors and transformation systems in plants

The patents of this family are directed to expression vectors for plant transformation containing chimeric genes that comprise a hpt gene. The hpt gene, also noted as an aphIV gene, serves as the basis for the selection of transformed plant cells.

The chimeric genes of the claimed invention contain from 5′ to 3′ direction:
a) a plant-expressible promoter sequence;
b) an aphIV gene which encodes a hygromycin phosphotransferase enzyme (US 5668298) or
a functional portion of it (US 6048730); and
c) a terminator signal sequence.

The US patent 5668298 claims a particular plasmid, pCEL40, which contains the promoter and the first 11 amino acids of the octopine synthase (OCS) gene of Agrobacterium Ti plasmid fused to an aphIV gene.

The independent claim of the European patent of this family is broader than in the United States patents. The components of the chimeric gene are not spelled out with the exception of “a coding region that confers hygromycin resistance on the plant cell”.

Patents members of Family 3
Country Granted Patent No. Filing Date Issue date
Europe* EP 186425 B1 December 18, 1985 September 30, 1992
Japan JP 2815837 B2
JP 3090926 B2
December 28, 1995
December 20, 1985
October 27, 1998
September 25, 2000
United States US 5668298
US 6048730
June 7, 1995
September 19, 1990
September 16, 1997**
April 11, 2000
* The European patent was converted to a national patent in Belgium (BE), France (FR), Germany (DE), Great Britain (GB), Italy (IT); Liechtenstein (LI); Luxemburg (LU); Netherlands (NL), Sweden (SE) and Switzerland (CH). There is a related patent application pending in Denmark.
** Patent term of both United States patents is 17 years from the date of issuance.
✝This United States patent was filed by and directly granted to Novartis. To view or download the patents as PDF files, click on EP 186425 B1 (1.3 kb),
US 5668298 (1.0 kb) and US 6048730 ( 0.9 kb).

Thus, in Europeany chimeric gene for plant transformation conferring resistance to hygromycin is possibly covered by the patented invention. Although, the United States patents are a bit more specific with respect to the comprising elements of the chimeric gene, the chimeric construct is described in such generic terms that it practicably does not leave much freedom to operate for other constructs for plant transformation having an aphIV gene without infringing the patents.