Mutational profile of the regenerative process andde novogenome assembly of the planarianSchmidtea polychroa

ABSTRACT Planarians are organisms with a unique capacity to regenerate any part of their body. New tissues are generated in a process that requires many swift cell divisions. How costly is this process to an animal in terms of mutational load remains unknown. Using whole genome sequencing, we defined the mutational profile of the process of regeneration in the planarian species Schmidtea polychroa . We assembled de novo the genome of S. polychroa and analyzed mutations in animals that have undergone regeneration. We observed a threefold increase in the number of mutations and an altered mutational spectrum. High allele frequencies of subclonal mutations in regenerated animals suggested that relatively few stem cells with high expansion potential regenerated the animal. We provide, for the first time, the draft genome assembly of S. polychroa , an estimation of the germline mutation rate for a planarian species and the mutational spectrum of the regeneration process of a living organism.