nptII gene in combination with paromomycin as a selective agent

EP 927765 A1
Title Method for selecting transformed cells
Application No. and Filing date EP 98933906.4
July 23, 1998
Publication date July 7, 1999
Remarks Related patent applications filed in China (CN 1239513 T) and in Canada (CA 2265570). The Canadian application corresponds to the PCT application WO 99/05296. The claims as filed of the Canadian application are worded the same as the European application.
The related Australian patent application AU 83568/98 was abandoned on February 21, 2002.
To view or download the patent application as a PDF file, click on EP 927765 A1 ( 0.6 kb).

Japan Tobacco has filed a European patent application directed to the use of the nptII gene in combination with the antibiotic paromomycin for the selection of transformed rice cells.

The nptII gene as a selectable marker for monocot plants, especially rice, has not been very effective when used in combination with kanamycin as a selective agent. This antibiotic negatively affects the regeneration of the transformed plants. The performance of G418 as a selective agent for monocots is better, but there is still poor transformation efficiency. The applicants claim that the combination of the nptII gene with paromomycin constitutes a highly efficient rice transformation system.

The filed claims of the European patent application are limited to:

  • a method to select transformed rice cells, which contain a gene of interest and a paromomycin resistance gene by applying paromomycin to the medium;
  • a method for producing rice transformants by Agrobacterium-mediated transformation of rice cells with a construct having a gene of interest and a paromomycin resistance gene. The transformed cells are selected with paromomycin and regenerated into complete plants; and
  • transformed rice selected following the method mentioned above.

The paromomycin resistance gene is not limited to the nptII gene in the filed independent claims. Thus, the invention might encompass any gene that confers resistance to paromomycin, including the nptII gene. The use of paromomycin and a paromomycin resistance gene for the selection of rice plants is one of the main limitations of the invention as filed. It is not possible to ascertain the exact limitations of the claims as the application has not been granted yet.