Late Blight of Potato and Tomato in the Genomics Era

Tremendous progress in the availability of genomic data has been made in the past decade. With the advent of high throughput and affordable DNA sequencing, the entire hereditary blueprint of an organism can be determined. A widespread transition into research enabled by the tools and resources of genomics is consequently occurring, and it has already affected countless disciplines within the biological sciences, including plant pathology. This new era of research allows a comprehensive study of gene structure and function and has already delivered tremendous insights into the basic biology of living organisms. Genomics offers new opportunities for applied biological sciences and is poised to impact plant health and plant disease management. More than 150 years have elapsed since Phytophthora infestans caused the Irish potato famine, but strategies for managing potato and tomato late blight often remain unsustainable and costly. In effect, P. infestans continues to cost billions of dollars annually through losses in potato and tomato production and increased fungicide costs (15,45,47,48). In the United States and other developed countries, chronic use of chemicals to manage late blight reduces the profit margins of farmers and is not always successful. Most populations of the pathogen are resistant to metalaxyl (and the active enantiomer mefenoxam), which had previously been very successful for controlling P. infestans (19,47). In developing countries, late blight also affects subsistence potato production. Recent epidemics in the 1990s, notably in eastern Europe, have caused significant losses in yield (20,46). In 2003, potato production was nearly eliminated in Papua New Guinea, one of the few countries in the world that was previously free of the disease (4). Remarkably, the disease spread through the entire country within 2 months of first incidence. Disturbing reports predict that potato late blight will continue to cause food shortages and hunger in several parts of the world (20,46).