Characterization of Experimental Evolution and DNA Methylation in the Rice Blast Fungus

Much progress has been made in understanding the genetic basis of fungal development and pathogenicity during the last few decades. However, there are still wide gap in knowledge on fungal evolution and biology. Recently, rapid development in high throughput sequencing technology made it possible to put forth the hypothesis that couldn’t be tested before. Applying molecular biology tools and high throughput sequencing, here I address the experimental evolution and contribution of an epigenetic component-DNA methylation to development of a model plant pathogenic fungus, Magnaporthe oryzae. .;In chapter 1, I summarize important aspects of M. oryzae as a model plant pathogen to study the evolution and DNA methylation in filamentous fungi. I also give a brief brief description of experimental evolution and DNA methylation, which will serve as a general introduction to the next chapters.;In chapter 2, I present the application of method to study of experimental evolution in M. oryzae. Evolved strains (derived strain in chapter 2) under laboratory conditions were obtained and characterized at both phenotypic and molecular level in comparison to the parental strain. Monitoring the phenotypic and genotypic changes revealed that phenotypic changes are not proportional to genotypic changes. Analysis of mutations within the genome of the derived strain showed that genetic drift and selection shape the mutational landscape of the derived genomes, and that main source of mutations under laboratory condition are oxidative damages and/or UV.;In chapter 3, I investigate the DNA methylation during fungal development. DNA methylation in fungi is considered to be a stable mark for transcriptional silencing of transposable element. Analysis of DNA methylation in M. oryzae showed that DNA methylation pattern in the fungal genome undergoes massive reprogramming during pathogenic development, suggesting new paradigm to evolution and function of fungal DNA methylation. I argue that such reprogramming of fungal DNA methylation is analogous to epigenetic reprogramming during mammalian development. I conclude the chapter discussing the similarities and differences between two systems.