Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
Haas. B. J Handsaker. R. E Cano. L. M Kamoun. S Zody. M. C Jiang. R. H. Y Grabherr. M Kodira. C. D
Nature ; 2009 [Vol.461] Pages:393-398
Abstract
Phytophthora infestans is the most destructive pathogen of potato and a model organism for the oomycetes, adistinct lineage of fungus-likeeukaryotes that are related to organisms such as brown algae and diatoms. As the agent of the Irish potato famine in the mid-nineteenth century, P. infestans has had a tremendous effect on Human history, resulting in famine and population displacement. To this day, it affects world agriculture by causing the most destructive disease of potato, the fourth largest food crop and a critical alternative to the major cereal crops for feeding the world’s population. Current annual world wide potato crop losses due to late blight are conservatively estimated at $6.7 billion. Management of this devastating pathogenis challenged by its remarkable speed of adaptation to control strategies such as genetically resistant cultivars. Here were port these quence of the P. infestans genome, which at ~240 mega bases (Mb) is by far the largest and most complex genome sequenced so far in the chromalveolates. Its expansion results from a proliferation of repetitive DNA accounting for ~74% of the genome. Comparison with two other Phytophthora genomes showed rapid turnover and extensive expansion of specific families of secreted disease effector proteins, including many genes that are induced during infection or are predicted to have activities that alter host physiology. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome. This probably plays a crucial part in the rapid adaptability of the pathogen to host plants and underpins its evolutionary potential.
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