A conduit for T-DNA through the plant cell membrane: dig it yourself!

Abstract

Agrobacterium tumefaciens is a plant-pathogenic bacterium notorious for its ability to redirect the plant metabolism to meet the pathogen's gourmandise. This is achieved by the stable genetic modification of the host plant after integration of the bacterial T-DNA into the plant genome, a unique example of inter-kingdom DNA transfer. The T-DNA stems from the bacterial tumor-inducing (Ti) plasmid and travels as a single-stranded molecule from the bacterial to the plant cell, tipped with a covalently linked single molecule of VirD2 protein. Once inside the plant cell, many, cooperatively bound VirE2 protein molecules coat the T-DNA. Laboratory strains of Agrobacterium have had to endure significant disarmament of their pathogenicity and subsequent widespread exploitation as a tool in plant transformation. The genes on the Ti plasmid can be reduced to those that are essential for a successful T-DNA transfer, and sequences intended for plant genome integration are routinely inserted into the T-DNA as ‘stowaways’.