Major QTL Affect Resistance to Infectious Pancreatic Necrosis in Atlantic Salmon (Salmo salar)

Infectious Pancreatic Necrosis (IPN) is a viral disease currently presenting a major problem to the production of Atlantic salmon (Salmon salar). IPN can cause significant mortality to salmon fry within freshwater hatcheries, and to smolts following transfer to seawater, although challenged populations show clear genetic variation in resistance. To determine whether this genetic variation includes loci of major effect, a genome-wide QTL scan was performed within ten large full-sib families that had received a natural seawater IPN challenge. To utilise the large difference between Atlantic salmon male and female recombination rate, a two-stage mapping strategy was employed. Initially, a sire-based QTL analysis was used to detect linkage groups with significant effects on IPN resistance, using ca. two to three microsatellite markers per linkage group. A dam-based analysis with additional markers was then used to confirm and position any detected QTL. Two genome-wide significant QTL and one suggestive QTL were detected in the genome scan. The largest QTL was mapped to linkage group 21, and was significant at the genome-wide level in both the sire and dam-based analyses. The identified QTL can be applied in marker-assisted selection programmes to improve the resistance of salmon to IPN and reduce disease-related mortality.

Key Words: Atlantic salmon, Disease Resistance, Marker-assisted selection, QTL, Recombination

Online ISSN: 1943-2361  Print ISSN: 0016-6731
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