"Listening in" on how a bacterium takes over the plant vascular system.

Bacteria that infect the plant vascular system are among the most destructive kind of plant pathogens because pathogen proliferation in the vascular system will sooner or later shut down the plant's water and nutrient supply and necessarily lead to wilting and, in the worst case, death of the entire plant. How bacterial plant pathogens adapted to life in the plant vascular system is still poorly understood. As described in a recent article, Caitilyn Allen and her group studied the archetypical vascular pathogen Ralstonia solanacearum, the causative agent of bacterial wilt disease in almost 200 crop and ornamental plant species, and they have described the results of a microarray analysis that allowed them to "listen in" on the pathogen's sabotaging activity inside the plant [J. M. Jacobs et al., mBio 3(4):e00114-12, 2012]. Besides gaining for the first time an almost complete picture of R. solanacearum gene expression during infection, this approach allowed revision of a wrong assumption about the activity of the pathogen's type III secretion system during infection and uncovered the importance of sucrose as an energy source for vascular pathogens like R. solanacearum.