Rhizobium radiobacter

Rhizobium radiobacter (formerly known as Agrobacterium tumefaciens) is found in soil. It can infect over 140 plant species including important crop plants like nuts, fruits, and vegetables, plus non-food plants including rose, elm, and willow. Entering via wounds, it colonises plant tissues without killing the plant. Instead it triggers abnormal growth, leading to galls (tumours) and other kinds of overgrowth. For example, in tomatoes it causes excessive root proliferation known as root mat disease (also known as hairy roots and crazy roots). With the plant’s resources being diverted to the infected overgrowing areas, the rest of the plant weakens.

This bacterium has been very well studied as it is a natural genetic engineer. It transfers some of its DNA into the host plant genome, forcing the plant to make food for the bacterium. Understanding this mechanism has underpinned many breakthroughs in plant genetic engineering and biotechnology. It is still used for research now – researchers on our Disease Suppressive Microbes project are using it as a model organism to study whether synthetic soils and cocktails of beneficial microbes might help prevent and treat tomato root mat disease.

Find out more about Rhizobium radiobacter via these resources:

Root mat disease on tomato (Credit: AHDB)
Root galls on pecan (Credit: Clemson University)