Location: Cool and Cold Water Aquaculture Research
Title: Mapping of QTL for bacterial cold water disease resistance in rainbow trout Authors
Submitted to: Aquaculture Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 17, 2012
Publication Date: February 25, 2013
Citation: Palti, Y., Vallejo, R.L., Welch, T.J., Evenhuis, J., Leeds, T.D., Gao, G., Liu, S., Rexroad III, C.E., Wiens, G.D. 2013. Mapping of QTL for bacterial cold water disease resistance in rainbow trout. Aquaculture Conference Proceedings. P0296. Technical Abstract: Bacterial cold water disease (BCWD) causes significant economic loss in salmonids aquaculture. We previously detected genetic variation in survival following challenge with Flavobacterium psychrophilum (Fp), the causative agent of BCWD in rainbow trout, and a family-based selection program to improve resistance was initiated at the National Center for Cool and Cold Water Aquaculture (NCCCWA) in 2005. In order to understand the genetic architecture underlying variation in BCWD resistance, we made select crosses in 2007 and 2009 and phenotyped fish using Fp injection challenge. In 2009, fifteen families were created with a predicted F2 or back-cross (BC) segregation of major loci based on full-sib family performance of the grandparents and parents. From each F2/BC family, 200-260 fish were challenged in 4-6 replicates per family. Whole genome QTL scanning of three families with approximately 270 informative microsatellite loci per family spaced at an average interval size of approximately 6cM along the rainbow trout chromosomes was conducted. Two traits were mapped, Survival Status (dead or alive) on day 22 post challenge and Survival Days. Eight significant (LOD greater than 4.0) QTL and 22 suggestive (LOD greater than 3.0 and smaller than 4.0) QTL were identified for the two survival traits on 15 of the rainbow trout 29 chromosomes. One significant QTL on Chromosome OMY8 was accounted for 41% of the phenotypic variance in survival status and 29% in survival days in one of the three families. The QTL will be further tested by genotyping of half-sib families and test crosses of fish from this germplasm with unrelated germplasm from other rainbow trout broodstocks, including our spleen size QTL mapping population.