The cointegrate vector is a single plasmid vector system created by unifying two plasmids via homologous recombination. One of the plasmid in the pair carries DNA insert and the other carries the vir genes for the transfer of the insert from Agrobacterium to plants. When the two plasmids combine, the resultant is a cointegrate vector that can be used to transform plant cells. A quick explanation of the whole procedure for students of BSc & MSc. Happy Learning!!