Ralstonia Phage

Ralstonia solanacearum causes significant crop losses in many plant species, especially potatoes

Ralstonia solanacearum is a soil bacterium which causes wilt and rot diseases in a wide variety of economically important plants, including potatoes, tomatoes, pepper, aubergine, and tobacco. The most serious of these is brown rot of potatoes which affects 1.7 million hectares in approximately 80 countries, leading to worldwide crop losses of hundreds of millions of pounds. The disease mainly spreads through contaminated tools, soil, and groundwater, and transport of infected plants. Although not currently a major problem in the UK due to strict quarantine and surveillance of the UK river network, it could be devastating if new strains are introduced (as recently happened in the Netherlands and elsewhere in mainland Europe).

Phages (also known as bacteriophages) are viruses which can infect and kill bacteria. Phages are found abundantly in nature, wherever bacteria are present, including soil, water reservoirs, and plant microbiomes. Phages are also very specific, only killing certain bacteria. This means they could potentially be used as biocontrol agents to treat R. solanacearum infections without adversely affecting other microbes.

Find out more about bacterial wilt caused by Ralstonia solanacearum

This research studied the feasibility of using phages as biocontrol agents for Ralstonia solanacearum

Using tomatoes as a model system, we explored the potential of Ralstonia-specific phages to reduce bacterial wilt disease symptoms, decrease pathogen abundance, and observe the potential effects on the broader soil microbiome. First, we identified phages which could safely and effectively function as precision biocontrol agents against R. solanacearum. As bacteria can evolve phage-resistance, we deliberately allowed the bacteria to become resistant to the phage by culturing them together. In collaboration with iMEAN (Toulouse, France) we created a metabolic model of Ralstonia solanacearum. This helped us to understand how genetic changes, like phage-resistance mutations, might affect virulence and disease development.

To establish whether phage treatments are safe for plants, we compared differences in gene expression in tomatoes inoculated with phage-susceptible or phage-resistant pathogens. We also examined the soil microbiome before and after phage treatment. In collaboration with APS Biocontrol (Dundee, UK) we assessed the feasibility of spray-drying phages as a first step to developing commercial phage products.

To find out more about this project contact Ville Friman or Andrea Harper.

Download a Ralstonia Phage project summary including findings and recommendations

Publications and other outputs from the Ralstonia Phage project

Visit the Ville Friman’s Lab website

Visit Andrea Harper’s Lab website

Ralstonia Phage research summary Download

Photographs from the Ralstonia Phage Project Research

Healthy (back) and diseased (front) tomato seedlings infected by Ralstonia solanacearum pathogen. Image copyright: Ville-Petri Friman.
After entering plant roots (A), Ralstonia solanacearum (B) invades the xylem vessels and rapidly spreads to aerial parts of the plant throughout the vascular system. Typical wilting symptoms result from an excessive production of extracellular polysaccharides that alter water fluxes within the plant (C). Image copyright: Ville-Petri Friman and Zhong Wei.
Clearing zones showing the killing of R. solanacearum pathogen by phages (A). Transmission Electron Microscopy of phages infecting R. solanacearum cells (B). Image copyright: Ville-Petri Friman and Zhong Wei.