General Monocot Transformation Methods
Japan Tobacco (in Japan), Rhône-Poulenc Agro (in France), University of Guelph (in Canada) and recently, Paradigm Genetics (in the US), the Department of Primary Industries of Queensland (AU) and the National Institute of Agrobiological Resources (in Japan) have granted patents or patent applications directed to methods for Agrobacterium-mediated transformation of any monocot with a gene of interest. The main difference among them lies in:
- the initial plant tissue or explant used for the transformation process, and
- the application of additional treatments, such as vacuum infiltration or the addition of phenolic compounds to facilitate the transformation process.
Japan Tobacco claims the transformation of a monocot callus during a dedifferentiation process and the transformation of the scutellum of an immature embryo prior to dedifferentiation. Thus, these patents granted in the United States and Australia cover transformation of monocot tissues that are widely and commonly used. In the United States, the breadth of the claimed monocot callus transformation method appears limited only by the minimum number of days in culture before the transformation process takes place. This time limit is not part of the claims in either the Australian patent or European patent application.
Rhône-Poulenc Agro (now Bayer Crop Science) claims the transformation of a monocot inflorescencevia Agrobacterium. The inflorescence can be dissected and then transformed. Alternatively, callus formation is induced from an inflorescence in culture, and the derived callus is transformed withAgrobacterium. A transgenic monocot plant is then regenerated from the transformed inflorescence-derived callus. The invention is thus limited to transformation of a monocot inflorescence. Other tissues are not part of the scope of the claims.
In contrast to the previous two inventions that disclose particular tissue types for transformation, the Paradigm Genetics application discloses the use of vacuum infiltration in the presence of a phenolic compound for monocot transformation with Agrobacterium. A limitation of the claims as filed in the patent application is the use of a monocot flower. An apparatus to perform vacuum infiltration of the monocot plant is also part of the disclosed invention. It remains to be seen what claim scope is ultimately granted.
The Department of Primary Industries of Queensland does not disclose a particular tissue to be transformed in its PCT patent application. Neither are particular conditions stated for the transformation process. One limitation of the claimed invention consists of formation of an organogenic callus by the transformed plant cells.
The University of Guelph has a US application derived from a PCT application. An Australian application lapsed in 2002. The applications describe the use of vacuum infiltration in combination with a phenolic compound for the transformation of a monocot with Agrobacterium.
The National Institute of Agrobiological Resources (Japan) has PCT and European applications that disclose a method for transforming a monocot by treatment of intact seed with Agrobacterium containing a recombinant gene of interest.