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Talk Title :
Meat and Potatoes: Two Genomic Tales from Agriculture
Date / Time / Location:
Thursday, May 6th 2010 – 4:00 PM
Room 232, Leacock Building.
Domestication of plants and animals marked a major turning point in human development, allowing sedentary societies to achieve tremendous growth through the maintenance of reliable sources of food. Growth of agricultural societies was accompanied by human-directed growth and evolution of domesticated species and, along with them, the pathogens that infected these species. I will present results from analysis of two very different genomic models: Phytophthora infestans, an oomycete plant pathogen that causes late blight of potatoes and tomatoes, and the domestic chicken, the largest source of animal protein for human consumption.
P. infestans was discovered in the 19th century and shown to be the cause of late blight, the disease responsible for the Great Irish Famine and other widespread potato crop failures throughout Europe. The pathogen spreads rapidly and is highly destructive on susceptible plant strains. Despite over a century of efforts at control through breeding resistant plants, late blight remains a major threat to world’s food supply, destroying over $6 billion of potatoes every year. Widespread outbreaks have occurred in both America and Europe in the past two years. Our analysis of the genome of P. infestans suggests that its ability to overcome control efforts may result from a highly dynamic genome that is undergoing rapid gene turnover, allowing it to diversify easily in the face of new selective pressures.
The chicken, Gallus gallus, was domesticated around 8,000 years ago in south Asia and has spread worldwide. Extensive selection by humans has led to domestic birds that show a wide range of color, growth, and reproductive variation compared to their wild ancestors, the red junglefowl. We have used SOLiD technology to resequence pools of birds selected from multiple domestic lines maintained for different production purposes and from red junglefowl populations. These data reveal multiple loci that appear to have been under strong selection during development of the domestic chicken, including one potential early domestication gene with a role in reproductive control. We also identified a number of sites of gene deletion that are fixed in one or more domestic chicken breeds, two of which have striking growth phenotypes.
These two diverse studies, drawing on the selective pressures at work in the farm environment, illustrate basic principles of how organisms evolve at a molecular level and adapt to both natural and human selective pressures. They further provide some guidance for agricultural improvements. Our P. infestans results suggest new methods for monitoring and may lead to better deployment of resistant strains. Our chicken findings identify multiple sites likely to have been selected for important production traits, providing targets for future breeding improvement as well as advancing our understanding of the chicken as a model organism.