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The linear mitochondrial genome of the quarantine pest Synchytrium endobioticum; insights in the evolutionary history of an obligate biotroph

Bart van de Vossenberg: Wageningen University and Research

<div>Chytridiomycota (chytrids) inhabit terrestrial and aquatic environments, and represent a basal lineage in true fungi. <span>Most of the described chytridiomycota are free living saprophytes, but several species are notorious pathogens for plants or amphibians. <i>Synchytrium endobioticum</i> is an obligate biotroph chytrid causing potato wart disease. Quarantine measures have been implemented worldwide to control the disease and to prevent its spread. To determine taxonomical relationships, and to gain insights into the evolutionary history of this plant pathogen we assembled and annotated the mitochondrial genome of <i>S. endobioticum </i>and generated mitochondrial genomes for five additional chytrid species. The mitochondrial genome of <i>S. endobioticum</i> is a linear 72,865 bp molecule with terminal inverted repeats that encodes 14 mitochondrial genes typically found in fungi. Polymorphisms in 30 <i>S. endobioticum </i>isolates shows clustering in four main mitochondrial lineages, and from </span><span>our data we conclude that the pest was introduced at least three times in Europe. Strains of pathotype 2(G1) and 6(O1) were represented in two mitochondrial lineages, showing that these pathotypes emerged independently. Variations within a strain for polymorphic sites were observed and seem to be consistent in different mitochondrial lineages suggesting that <i>S. endobioticum</i> strains are communities of different genotypes with conserved composition.</span></div>