Page last updated at 00:00 GMT, Thursday, 10 September 2009 01:00 UK

Potato famine blight DNA decoded

Potato blight costs the industry about 3bn a year

Scientists have decoded the DNA secrets of the notorious pathogen that caused the Irish potato famine, which led to the deaths of a million people.

Phytophthora infestans, or "potato blight" still costs the industry more than £3bn a year due to crop failures.

The research, which involved the Scottish Crop Research Institute in Dundee, found the pathogen is highly adaptable and can change quickly.

The study will be used to try and curb the impact of the plant disease.

Scientists discovered that the organism boasts an unusually large genome size, more than twice that of closely related species, and an extraordinary genome structure.

Together, they enable the rapid evolution of genes, particularly those involved in plant infection.

'Many clues'

Studies have revealed that the pathogen can outsmart its plant hosts because of its ability to change and can adapt to new plant hosts, including tomatoes or seemingly immune potato crops.

Dr Stephen Whisson, of the SCRI, said the study could have a huge impact on the industry.

He said: "The utility of the genome sequence in our research against late blight cannot be overstated.

"It gives us many clues as to which genes might be absolutely required for late blight disease development.

"The products from these essential 'disease' genes are then potentially useful to target for resistance in potato breeding programmes, or in development of more specific and environmentally friendly control chemicals."

P. infestans thrives in cool, wet weather, and can infect potatoes, tomatoes and other related plants, causing a "late blight" disease that can decimate entire fields in just a few days.

Long considered a fungus, it is now known to be a member of the oomycetes or "water moulds", which are more closely related to brown algae than to fungi.

The study's findings, which involved researchers from all over the world, are published this week by Nature.

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