Location: Cool and Cold Water Aquaculture Research
Title: SELECTIVE BREEDING AND GENETIC MAPPING OF DISEASE RESISTANCE IN RAINBOW TROUT Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 26, 2006
Publication Date: June 26, 2006
Citation: Palti, Y., Rexroad Iii, C.E., Welch, T.J., Wiens, G.D., Silverstein, J., Vallejo, R.L. 2006. Selective breeding and genetic mapping of disease resistance in rainbow trout. Meeting Abstract. Presented at The 9th International Symposium of The International Association for Genetics in Aquaculture, June 26-30, 2006 at Montpellier, France. Meeting Book of Abstracts p. 81. Technical Abstract: The USDA/ARS National Center for Cool and Cold Water Aquaculture (NCCCWA) is working to integrate molecular genetic technologies into a family based selective breeding program aimed at the genetic improvement of rainbow trout for aquaculture production efficiency. A genetic linkage map is being constructed using more than 1,000 microsatellite markers to facilitate QTL and linkage disequilibrium (LD) mapping of desirable traits. The microsatellites were derived from repeat-enriched libraries, ESTs and BAC clones that harbor genes of interest. The latter are used to identify major histocompatibility (MH) haplotypes in the NCCCWA broodstock and to map genes involved in immune response. Two disease trials with two gram negative bacterial pathogens were conducted. The 2004 brood year families were challenged with Yersinia ruckeri, the causative agent of enteric red mouth disease, and the 2005 families were challenged with Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease and rainbow trout fry syndrome. Overall mortality rates were greater than 70% in the F. psychrophilum challenge and greater than 20% in the Y. ruckeri challenge with large variation among families. Resistance to each disease is assessed as both binary (died/survived) and continuous (post challenge days to death) traits. Phenotypic variation and additive genetic variation are being estimated using mixed models of survival analysis. The parents of the 2004 and 2005 brood year families are being genotyped with markers linked to the four major MH genomic regions to assess LD between MH haplotypes and resistance to the two bacterial diseases. The impact of MH sequence variation on selective breeding for disease resistance in aquaculture will be discussed.