Question: Do the Agrobacterium replace their victim's DNA or do they just add to them and how do they implement the DNA if they only put the DNA in

Carmen Denman answered on 9 Mar 2015:

Hi Wrichik 1999,

Wow, specific question! A bit out of my expertise really, but thankfully I had an amazing Professor at University in Oregon (USA) who is a world expert on Agrobacterium and I’ve looked his profile and publications up to help me answer your question. It is a very complicated question but I’ve tried to simplify it! By victim, you mean plant – but I like victim, sounds much more vicious!

Agrobacterium tumefaciens is the only prokaryote known to transfer genes to a eukaryote. A. tumefaciens is important both as a pathogen and as a means to introduce novel genes into plants. Many laboratorys around the world study secreted virulence proteins that mediate transfer of tumor-inducing genes from Agrobacterium into plant cells.

A. Tumefaciens translocates several virulence proteins and oncogenic DNA into plant cells through a type IV secretion system. Similar secretion systems are required for the virulence of many bacterial species that infect humans. However, the Agrobacterium secretion system is the best characterized because A. tumefaciens is easier to study than most animal pathogens.

A. tumefaciens transfers specific genes into plant cells where these genes integrate into plant nuclear DNA. Plant tumor cells express transferred genes responsible for tumor growth and for production of novel compounds that the tumor-inducing bacteria use as nutrients. Thus, A. tumefaciens engineers plant cells to grow rapidly and produce nutrients for the bacteria. Research work will continue to focus on transfer and integration of A. tumefaciens DNA in plants.

Hope that is a good enough answer, if not, I shall put you in touch with a proper plant biologist if not!
Cheers,
Carmen