Identification of EMS-Induced Mutations in Drosophila melanogaster by Whole-Genome Sequencing

Next-generation methods for rapid whole-genome sequencing enable the identification of single-base-pair mutations in Drosophila by comparing a chromosome hearing a new mutation to the unmutagenized sequence. To validate this approach, we sought to identify the molecular lesion responsible for a recessive EMS-induced mutation affecting egg shelf morphology by using Illumina next-generation sequencing. After obtaining sufficient sequence from larvae that were homozygotis for either wild-type or mutant chromosomes, we obtained high-quality reads For base pairs composing similar to 70% of the third chromosome of both DNA samples. We verified 103 single-base-pair changes between the two chromosomes. Nine changes were nonsynonymous mutations and two were nonsense initiations. One nonsense imitation was in a gene, encore, whose mutations produce an egg shelf phenotype also observed in progeny of homozygous mutant mothers. Complementation analysis revealed that the chromosome carried a new functional allele of encore, demonstrating that one round of next-generation sequencing can identify the causative lesion for a phenotype of interest method. This new of whole-genome sequencing represents great promise for mutant mapping in flies, potentially replacing conventional methods.