Scientists have made a key discovery into the genetics of the bacteria thatcauses blackleg, an economically damaging disease of potatoes, that couldlead to new ways to fight the disease. The researchers at the University ofCambridge, funded by the Biotechnology and Biological Sciences ResearchCouncil (BBSRC), found that if a particular gene is inactivated in thebacterium
Erwinia carotovora, its ability to damage the plant and causedisease is severely impeded. The research was recently published in theJournal of Bacteriology. Erwinia carotovora can cause disease in a wide range of plants, includingcarrots, tomatoes and onions, but is best known in temperate regions forcausing blackleg and soft rot in potatoes. Its success partly lies in itsability to produce enzymes which break down its host's cell walls. Thedegraded cell walls provide nutrients to the bacterium, and so aid itssurvival and growth.
The Cambridge researchers discovered that if they inactivated a gene calledrelA, which helps the bacteria recognise when nutrients are running low,then the bacteria's ability to export enzymes to break down the plant's cellwalls is also abolished.
Research leader Dr Martin Welch explains: "Blackleg is a significanteconomic problem, substantially reducing crop yields.
"We have shown that the production of cell wall degrading enzymes isgenetically linked to not only signalling abilities but also to thebacterium's nutritional status. This has important implications forresearchers looking for new ways to control the disease. By improving ourunderstanding of how Erwinia carotovora rots the plant, we can revealadditional, possibly novel targets for the eventual development of anti-rotagents. We have also opened up the potential to develop pesticides."
Dr Mike Storey, R&D Director of the British Potato Council, commented inresponse to the research findings: "Blackleg is one of the key diseasesacross all sectors of the British potato industry. The findings from theUniversity of Cambridge are important as they could offer novel solutions,both to help store potatoes and to control the disease.
"Soft rots in particular are a concern for many crops going in store thisseason because of the warm and wet growing conditions. We rely on carefulstorage management as most varieties of potato have no inbuilt resistance tosoft rot and there are no available pesticides."
