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United States Department of Agriculture

Agricultural Research Service

Research Project: UTILIZATION OF GENOMICS FOR IMPROVING PRODUCTION TRAITS IN COOL AND COLD WATER AQUACULTURE

Location: Cool and Cold Water Aquaculture Research

Title: Validation of linkage between BCWD resistance and spleen size QTL on Omy19 in rainbow trout: Pleiotropy versus linkage

Authors
item Vallejo, Roger
item Palti, Yniv
item Liu, Sixin
item Marancik, David
item Welch, Timothy
item Leeds, Timothy
item Evenhuis, Jason
item Rexroad, Caird
item Wiens, Gregory

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 18, 2013
Publication Date: January 12, 2014
Citation: Vallejo, R.L., Palti, Y., Liu, S., Marancik, D.P., Welch, T.J., Leeds, T.D., Evenhuis, J., Rexroad III, C.E., Wiens, G.D. 2014. Validation of linkage between BCWD resistance and spleen size QTL on Omy19 in rainbow trout: Pleiotropy versus linkage. Plant and Animal Genome Conference. 361.

Technical Abstract: Bacterial cold water disease (BCWD) is caused by infection with Flavobacterium psychrophilum, and results in significant economic losses in salmonid aquaculture. Previously, we identified a major QTL for BCWD resistance on Omy19 (h2q=0.57-0.67) as well as a QTL for surrogate measures of disease resistance (SW=spleen weight and SI=spleen index). The objectives of this study were to (1) validate the observed linkage of BCWD resistance with spleen size in an additional genetic background; and (2) test the hypothesis of “close linkage” versus “complete pleiotropy”. We developed four full-sib families whose offspring were evaluated for BCWD resistance, SW and body weight. A total of 800 offspring were genotyped with eight STR markers from Omy19. We estimated genetic correlation between BCWD resistance and spleen size by fitting a multivariate mixed model. We then ran univariate and bivariate linkage analysis using half-sib family regression analysis with GridQTL and variance components method with Solar. We estimated positive non-significant genetic correlation rg(survdays, SW)=0.21 with heritability h2survdays=0.42 and h2SW=0.65. We validated significant and suggestive QTL for BCWD resistance (11-13 cM; h2q=0.03-0.21) and spleen size (8-33 cM; h2q=0.06-0.31) on Omy19. The bivariate linkage analysis of survstatus with SW detected a suggestive QTL (LOD=1.77; h2q=0.07) at 34 cM. None of the “close linkage” and “complete pleiotropy” models were rejected at P=0.05 significance level. Although non-significant, the log likelihood of “complete pleiotropy” models were higher than those of “close linkage” models at 0-25 cM region which provides a weak support for a pleiotropic QTL.

Last Modified: 7/23/2014
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