The phytopathogenic gram negative bacterial species Agrobacterium tumefaciens is a causal agent of crown-gall disease in plants, which is accompanied by tumor formation on plant roots.



Agrobacterium tumefaciens infects the plant through its Ti plasmid. The Ti plasmid integrates a segment of its DNA, known as T-DNA, into the chromosomal DNA of its host plant cells.



The vir region of Ti plasmid is not transferred to the host cell. This contains seven loci encoding for most of the virulence proteins (Vir proteins) required for T-DNA transport and integration into host genome.


T-DNA regions are delineated by two repeats (25 bp), designated as left and right borders. These regions contain genes which encode for proteins involved in biosynthesis of plant-type hormones and opine.


Immediately upon its discovery, the unique virulence strategy of Agrobacterium attracted attention of plant biotechnologists leading to the adaptation of Agrobacterium as an unprecedented tool for genetic transformation of plants.


Since the T-DNA region is determined only by delineating the left and right borders and not by any other DNA sequence, virtually any type of DNA can be placed between the borders and utilized for plant transformation.




Text by Stefania Paltrinieri, PhD students EpiSeedLink Marie Skłodowska-Curie Actions