Issue date: 30 January 2002

Up to 30% of harvested crops are lost through the effects of disease, according to scientists at the University of the West of England who are embarking on a three-year project to understand how bacteria invade plants.

The researchers will focus on a particular disease-causing organism that affects runner-beans, causing blighted leaves and a reduction in crop yields. Dr Dawn Arnold, a researcher and lecturer in the Centre for Research in Plant Sciences in the Faculty of Applied Sciences, is part of a team that has been awarded £164,000 of government research funds to conduct this novel research.

"We noticed that some strains of the bacteria result in disease, and some do not. It depends on the susceptibility of the plant, but also on the particular strain of the bacteria. Some plants are hypersensitive, and recognising a threat from an invading pathogen, some of the plant cells commit suicide, and kill themselves off to protect the plant as a whole. These areas might be tiny, just a small patch of brown cells barely visible to the naked eye."

Different strains of bacteria vary in their interaction with the plant according to their genetic makeup. In some cases they are in effect holding up a flag to the plant, and giving genetic signals that the plant is being invaded. In other cases, the disease-causing organism is able to invade the plant undetected.

The project will look at the genetic structure of the bacteria using the latest in DNA sequencing equipment. It aims to discover why some strains lose the so-called avirulence genes that give off these signals, thus appearing to reduce their effectiveness in colonising the host plant, and why some strains do not.

“If we can mimic this invasion mechanism in the laboratory, it could lead to an increased understanding of disease both in plants and in animals. It could also lead to the development of disease-resistant plants," said Dr Arnold. "It is like knowing your enemy. The more you know about it, the easier it is to defeat it."

Dr Peter Spencer-Phillips, Head of the School of Biosciences says that this award recognises UWE's excellence in plant sciences. “It is an intelligence-gathering exercise, which could help provide ways of meeting the challenge of producing and distributing safer food fairly in the years to come.”


Editor’s notes

 Dr Dawn Arnold is part of UWE's molecular genetics group. The project is headed by Professor Alan Vivian, and will be carried out in conjunction with Professor John Mansfield of Imperial College Wye, London.

 Funding has been provided by the Biotechnology and Biological Sciences Research Council.

 The bean pathogen under study is called Pseudomonas syringae pv. phaseolicola or Pph.

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