Binary and Shuttle Vectors - For the purpose of gene transfer in higher plants, a number of binary vectors were developed. These were based on the pPCV (plant cloning vector) series of plasmids. These vectors contain a conditional mini-RK2 replicon, which is maintained and mobilized by transacting functions derived from the plasmid RK2 replicon (origins-oriv and oriT).

The plasmid RK2 was introduced into both E. coli as well as Agrobacterium (GY 3101, which contains a Ti plasmid lacking T DNA) to facilitate replication of binary vectors in both these hosts, so that the vector can be maintained and shuttled between both hence the name shuttle vector also. Similar binary or shuttle vectors for maintenance and transfer between E. coli and yeast cells have also been designed