Summary of patents on modified binary vectors and methods
Several patents claim inventions built on the basic components of the binary vector system and methods for their use. The patents referred under this section are:
- Agrobacterium with more than one T-DNA or vir region. Leiden University and Schilperoort have a granted United States patent and a granted European patent on this subject matter. The multiple T-DNA or vir regions are integrated into the chromosome of Agrobacterium. Thus, the T-DNA and vir regions are present not only in the binary vectors, but also in the bacterial chromosome. Agrobacterium with these features is used for transformation of dicots and monocots of the families Liliaceae and Amaryllidaceae.
The main limitations of the patent claims are that they generally require having at least one of either T-DNA or vir region in the bacterial chromosome and that they only cover transforming monocots belonging to the families Liliaceae and Amaryllidaceae.
- Integration of foreign DNA in a plant target locus by homologous recombination. The United States and European patents granted to Mogen, now called Syngenta Mogen B.V., claim a vector with a region homologous to a part of the sequence of a target locus in the plant allowing homologous recombination between the target locus and the vector. This permits insertion of a gene of interest or a specific mutation in a particular locus of a plant genome.The claims require use of sequences from a plant target locus as part of an Agrobacterium vector in order to allow homologous recombination between the vector and the plant locus.
A series of binary vectors have been devised to suit different needs in a plant transformation. Different origins of replication for a plasmid, the size of the insert a binary plasmid can carry and the size of the plasmid itself are among the features considered for the design of plasmids that are highly stable, easy to manipulate and transfer across diverse host bacteria. For example, origins of replication that allow low copy or high copy number of plasmids in a host cell are the subject of several granted patents and patent applications. Specifically United States patent 6165780 (as PDF) and its related patent and applications filed by The National Institute of Agrobiological Resources (Japan) are directed to binary shuttle vectors containing two different origins of replication that confer stability and a low copy number of plasmids in both E. coli and Agrobacterium host cells. One of the claimed binary vectors can be used to insert a clone from a genome library into a plant for a complementation test.
More patents referring to this topic are likely to appear in the future as new combinations of origins of replication, number of restriction sites, capacity of the vector in terms of length of the carried insert, and number and nature of marker and reporter genes are envisioned and assembled in vector molecules according to the purpose or requirements of the research.
We analyze here one of those patents that refer to a binary vector maintained as a single copy in E. coli as well as in Agrobacterium and capable of carrying a large genome fragment.
- Binary vectors based on the bacterial artificial chromosome (BAC). Two United States patents and a European application assigned to Cornell refer to this topic. The binary vector that contains the T-DNA region has
- origins of replication for E. coli and Agrobacterium, wherein the plasmids are maintained as a single copy, and
- a unique restriction site for insertion of an exogenous sequence located between a right and a left T-DNA borders
Although binary BAC vectors are devised for cloning long fragments of DNA (around 150 Kb), this feature is not part of the claim scope and the claims are unrestricted as to the size of the plasmid. As a result, the claimed vector type has a fairly broad scope except that the origins of replication are very specific, that is, they must maintain plasmids as a single copy.
- Co-transformation with two binary vectors . The PCT and Australian applications recently filed by Pioneer Hi-Bred disclose the use of an Agrobacterium with two different binary vectors and a helper plasmid for co-transformation of plants. Because these are still applications, the scope of claims that may be granted is unknown.A related United States patent was granted to Pioneer Hi-Bred in July 2001. The granted claims are directed to the same subject matter as the filed claims of the Australian and the PCT application. Thus, the scope of the claims has already been defined in the United States.
Remember that any of the inventions referred to are protected only in the countries or jurisdictions where the patent rights have been conferred.