High profile plant disease research published by BBSRC researchers

10th Dec 2010

UK researchers funded by the BBSRC published a series of papers in Science magazine highlighting their successful work to sequence the genomes of a range of important plant-disease causing microbes. This research will contribute to future food security by creating opportunities to enhance our knowledge of plant disease resistance, as well as uncovering potential new targets for better control of these microbes.

Newly sequenced genomes of two types of mildew and the water mould that causes late blight in potatoes and tomatoes are published by researchers from across the BBSRC community.

Professor Janet Allen, BBSRC Director of Research and chair of the Global Food Security programme development board said "If we are to feed a growing global population we need to increase food production by around 50% over the next 20 years or so. With plant diseases resulting in up to 30% harvest losses, finding new methods to control them will be a very important part of this effort. It is very important to have good quality fundamental bioscience research to underpin any new technologies in this area and these genome sequences have the potential to enhance the progress of the research."

The two mildew microbes studied have been difficult to do experiments with. This is because it is not possible to grow them in artificial culture - they require living plants in order to survive.

Professor Allen continued "It is testament to the excellence of UK bioscience research that these scientists have managed to publish this world-class research despite the difficulties of studying the organisms in question."


Powdery mildew

Blumeria graminis is a powdery mildew fungus that affects barley and is especially a problem in cool, wet climates such as in the UK.

A team led by Dr Pietro Spanu at Imperial College London with other colleagues including Professor James Brown at the John Innes Centre (an institute of BBSRC) and Professor Nick Talbot at the University of Exeter has published the genome sequence of Blumeria graminis. In their paper they also discuss work that suggests that parts of the microbe's genome called transposons, which actually originate from other organisms, help the fungus to overcome the plant's defences.

"It was a big surprise," said Dr Spanu, "as a genome normally tries to keep its transposons under control. But in these genomes, one of the controls has been lifted. We think it might be an adaptive advantage for them to have these genomic parasites, as it allows the [fungus] to respond more rapidly to the plant's evolution and defeat the immune system."


Downy mildew

Hyaloperonospora arabidopsidis is a type of water mould or oomycete that causes yellow patches and fuzzy white mould on the leaves of the model plant Arabidopsis. Close relatives cause disease and damage on many crops including broccoli, grapes and lettuce.

Professor Jim Beynon at the University of Warwick co-ordinated this work in collaboration with Professors Jonathan Jones, at The Sainsbury Laboratory, and John McDowell and Brett Tyler, at Virginia Tech. Professor Beynon and colleagues are using the power of the interaction between the microbe Hyaloperonospora arabidopsidis and the highly studied laboratory plant Arabidopsis thaliana, to understand the close evolution of the host and pathogen and plant immunity in general.

Professor Beynon said "This pathogen has slimmed down key elements of its genetic material to avoid the plant's natural defenses by stealth. Despite this reduction, amazingly, it still sends over 100 proteins into plant cells to suppress the immune responses. Understanding how these proteins suppress plant immunity will enable us to select disease resistant crop plants and combat other plant disease such as potato blight and sudden oak death."


Late blight

Researchers led by Professor Sophien Kamoun at The Sainsbury Laboratory study the water mould (or oomycete) Phytophthora infestans, a destructive plant pathogen that causes late blight in potatoes and tomatoes.

Professor Kamoun's team sequenced two strains of P. infestans and three closely related species: P. ipomoeae, P. mirabilis and P. phaseoli that infect different plant families: morning glory, four o'clock and lima bean, respectively. Comparison of their genomes uncovers new information about how they adapt to new plants or to the evolving immune system of an existing host.

Professor Kamoun said "New strains of late blight pathogen cause regular new epidemics, as with the tomato strain that emerged in the US last year and is still spreading. It is important to understand how the pathogen adapts to its host plants. In this latest study, we have learnt more about how the pathogen evolves to attack new hosts.

"Such in-depth knowledge of the genetics of the pathogen will help us and other scientists worldwide find new ways to manage it. We can now suggest that the most evolutionarily stable genes are better targets for genetic resistance."

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