Toward Universal Forward Genetics: Using a Draft Genome Sequence of the Nematode<i>Oscheius tipulae</i>To Identify Mutations Affecting Vulva Development

Abstract

Mapping-by-sequencing has become a standard method to map and identify phenotype-causing mutations in model species. Here, we show that a fragmented draft assembly is sufficient to perform mapping-by-sequencing in nonmodel species. We generated a draft assembly and annotation of the genome of the free-living nematode <i>Oscheius tipulae</i>, a distant relative of the model <i>Caenorhabditis elegans</i> We used this draft to identify the likely causative mutations at the <i>O. tipulae cov</i>-3 locus, which affect vulval development. The <i>cov-3</i> locus encodes the <i>O. tipulae</i> ortholog of <i>C. elegans mig-13</i>, and we further show that <i>Cel-mig-13</i> mutants also have an unsuspected vulval-development phenotype. In a virtuous circle, we were able to use the linkage information collected during mutant mapping to improve the genome assembly. These results showcase the promise of genome-enabled forward genetics in nonmodel species.