A team of international scientists has successfully decoded the DNA of the potato blight pathogen. Spread by spores, Phytophthora infestans, or potato blight, is a form of water mould that can ruin crops in just a few days, and causes losses of about US$6 billion each year. The research, published in the journal Nature, discovered that the genome of the organism is between two and four times the size of closely related species and contains areas of repeated DNA sequences which enable fast mutation. These stretches of code are the key to plant infection, changing so rapidly that the host can't fight back. This explains how the pathogen is able to attack new varieties of potato that have been genetically bred to resist the infection. Scientists hope that with a better understanding of the genome it will now be easier to breed new blight resistant potato varieties and develop more effective treatments.