Genome-wide analysis of parasitic fitness traits in a non-model tree pathogen

摘要

The ascomycete fungus Ophiostoma novo-ulmi is the highly aggressive pathogen responsible for the current, highly destructive, pandemic of Dutch elm disease (DED). In spite of its economic and ecological impact, O. novo-ulmi is not considered a model species, even though this fungus is easily grown in the laboratory and amenable to standard genetic and molecular investigations. The nuclear genomes of O. novo-ulmi and related species O. ulmi were recently sequenced and annotated, thus providing new opportunities for deciphering the complex basis of parasitic fitness in these pathogens. Comparative in silico analyses with genomes from other, well-characterized fungal and bacterial genomes have confirmed that the DED pathogens possess several hundred orthologues of genes encoding putative pathogenicity factors. Physiological, molecular, genomic and transcriptomic approaches are currently being used for studying yeast-mycelium dimorphism, a trait that the DED fungi share with several other pathogens of plants and mammals. The response of O. novo-ulmi to specific external stimuli suggests that oxylipins may be involved in yeast-mycelium transition. Orthologues of genes encoding enzymes involved in the biosynthesis of oxylipins are present in the nuclear genome of O. novo-ulmi. Genome-wide analyses of gene expression in the yeast and mycelial phases have revealed that over 10 of the nuclear genes are differentially expressed between these conditions. Comparisons with transcriptomes of the human pathogens Candida albicans and Histoplasma capsulatum showed that regulation patterns differed among the three species, thus highlighting the importance of developing resources for non-model organisms such as the DED fungi.