Marker-assisted selection in a Pacific oyster population for an antiviral QTL conferring increased survival to OsHV-1 mortality events in Tomales Bay
Konstantin Divilov, Noah Merz, Blaine Schoolfield, Timothy J. Green, Chris Langdon
Abstract
Aquaculture of Pacific oysters (Crassostrea gigas) around the world is stymied by mortality events triggered by Ostreid herpesvirus 1 (OsHV-1). In Tomales Bay, California, where OsHV-1 is endemic, breeding through family-based pedigree selection has achieved considerable genetic gains in survival to mortality events. In this study, a genome-wide association study with unselected and selected oyster families was performed that led to the detection of one quantitative trait locus (QTL) on chromosome 8 of the Pacific oyster genome that was associated with survival to mortality events in Tomales Bay and explained 13% of the phenotypic variance. RT-qPCR was used to determine that the basal upregulation of two antiviral genes, IRF2 and Viperin, was also associated with this QTL. Marker-assisted selection for this QTL was performed and families selected in this manner had 47% greater survival breeding values than families selected using pedigree selection alone. Future fine-mapping of this QTL could potentially provide a mechanistic understanding of OsHV-1 tolerance in Tomales Bay.