Vectors Derived From pTi - The use of wild type pTi as a vector presents the following three problems.
1. Presence of oncogenes (iaaM, iaaH and ipt) in T-DNA, which causes a disorganised growth and a loss of regeneration potential of the cells having T-DNA in their genomes.

2. The large size of pTi makes the handling procedures during cloning tedius and cumbersome.

3. A general lack of unique cloning sites within the T-DNA, which are needed for the insertion of DNA segments to be cloned.

These problems have been resolved by deleting the oncogenes from the T-DNA (disarming) and by developing intermediate (IV; to finally yield cointegrate vectors) and binary vectors to facilitate gene cloning procedures.