Mechanisms of genomic, genetic, and phenotypic divergence in the Magnaporthaceae

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How do fungal populations adapt to infect new hosts or evolve new species? Either reconstructed statistically from genomic DNA and protein sequences, or observed in real time in the course of experimental evolution in the laboratory, we prove two key Darwinian concepts: natural selection on new variants (mutations) with those conveying adaptation (higher fitness) increasing in frequency in populations, and persistence of adaptive genotypes when hybrids between different adaptations have poorer fitness than their parents. The novel aspect is that we identify the genes in which mutations occur and the effects, in response to any stress we choose, of specific mutations, from the effect of a gene product to all ripple effects throughout the whole genome. Other speciation laboratories study existing species that evolved in events we cannot observe or reconstruct because they occurred millions of years ago. From one cell, in just 3 months, we incited speciation in 12 lab populations of baking/brewing/wine yeast. Using next-generation genome sequencing, population genomics, genetics, and transcriptomics, we have found 12 key mutations in four of the populations adapted to one of two stress environments, high salt or low glucose. Three of these mutations are in global regulators of gene expression with broad ripple effects. These same variants are found in wild vineyard yeast, not just in the lab. We propose to determine their importance in the wild in relation to how yeast uses food to produce energy. We are also using whole genomes to study an important group of plant-disease fungi, including Magnaporthe, cause of blast, the most important disease of rice worldwide, and Gaeumannomyces, cause of take all of wheat and other grains worldwide, including Canada. The objectives are to identify the genes and their variants caused by mutation that have caused diversification in these genera, specifically ability to change hosts and nutritionally exploit different grasses, including turf and cereal species. We hope to increase our ability to improve these crop species and to predict the direction of evolutionary change (in a changing world) in order to better manage disease.