IDENTIFICATION AND CHARACTERIZATION OF GENES AFFECTING COOL AND COLD WATER AQUACULTURE PRODUCTION
Location: Cool and Cold Water Aquaculture Research
Title: Evidence of major genes affecting bacterial cold water disease resistance in rainbow trout using Bayesian methods of complex segregation analysis
Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 2, 2009
Publication Date: January 9, 2010
Citation: Vallejo, R.L., Wiens, G.D., Rexroad Iii, C.E., Welch, T.J., Evenhuis, J., Leeds, T.D., Janss, L.L., Palti, Y. 2010. Evidence of major genes affecting bacterial cold water disease resistance in rainbow trout using Bayesian methods of complex segregation analysis. Plant and Animal Genome Conference XVIII. Paper No. 103.
Bacterial cold water disease (BCWD) causes significant economic loss in salmonid aquaculture. We previously detected genetic variation for BCWD resistance in our rainbow trout population, and a family-based selection program to improve resistance was initiated at the NCCCWA in 2005. The main objectives of this study were to determine the mode of inheritance of BCWD resistance and design informative crosses for mapping quantitative trait loci (QTL). A total of 10,603 juvenile fish from 105 full-sib families corresponding to three generations (2005, 2007 and 2009 hatch years) of the NCCCWA population were challenged by intraperitoneal injection with Flavobacterium psychrophilum, the bacterium that causes BCWD. Mortality was monitored for 21 days. Bayesian segregation analysis was used to fit mixed-inheritance threshold models to binary survival status (dead or alive), and predicted that ~53% of the phenotypic variation (~90% of the genetic variation) can be attributed to one locus or a small number of loci with major effects and either codominance or complete dominance for BCWD resistance. Partial dominance was rejected because the 95% highest posterior density region for the difference between the additive effect and absolute dominance effect included 0. In addition, a large number of loci with very small allelic effects underlie the genetic variation of resistance to BCWD. Estimated heritability of BCWD resistance was 0.59 and 0.62 when fitting mixed-inheritance and polygenic models, respectively. These findings provide the basis for designing informative crosses that will be used in genome-wide scans for QTL affecting BCWD resistance in rainbow trout.