Abstract
Asian seabass has suffered from viral nervous necrosis (VNN) disease. Our previous study has mapped quantitative trait loci (QTL) for resistance to VNN disease. To fine map these QTL and identify causative genes, we identified 6425 single nucleotide polymorphisms (SNPs) from 85 dead and 94 surviving individuals. Combined with 155 microsatellites, we constructed a genetic map consisting of 24 linkage groups (LGs) containing 3000 markers, with an average interval of 1.27 cM. We mapped one significant and three suggestive QTL with phenotypic variation explained (PVE) of 8.3 to 11.0%, two significant and two suggestive QTL with PVE of 7.8 to 10.9%, for resistance in three LGs and survival time in four LGs, respectively. Further analysis one QTL with the largest effect identified protocadherin alpha-C 2-like (Pcdhac2) as the possible candidate gene. Association study in 43 families with 1127 individuals revealed a 6 bp insertion-deletion was significantly associated with disease resistance. qRT-PCR showed the expression of Pcdhac2 was significantly induced in the brain, muscle and skin after nervous necrosis virus (NNV) infection. Our results could facilitate marker-assisted selection (MAS) for resistance to NNV in Asian seabass and set up the basis for functional analysis of the potential causative gene for resistance.
Highlights
IntroductionOur previous study has mapped quantitative trait loci (QTL) for resistance to viral nervous necrosis (VNN) disease
Asian seabass has suffered from viral nervous necrosis (VNN) disease
An average of 4.36 million reads were assigned to each offspring, 14.74 million and 19.05 million reads were assigned to sire and dam, respectively
Summary
Our previous study has mapped quantitative trait loci (QTL) for resistance to VNN disease To fine map these QTL and identify causative genes, we identified 6425 single nucleotide polymorphisms (SNPs) from 85 dead and 94 surviving individuals. The ever-growing demand for high-efficient aquaculture production to feed the world’s fast-growing population in the face of rapidly degenerating climate is still strong To meet this challenge, selective breeding programs are adopted to accelerate the genetic gain and the subsequent performance, resulting in substantial improvement of production in several cultured aquatic species[2]. A more advanced approach genomic selection (GS)[4], possesses the great potential to overcome these difficulties Those methods involve in using genetic markers in linkage disequilibrium (LD) with QTL or directly using quantitative trait nucleotide (QTN) to predict the phenotype and select the desirable individuals. A large number of polymorphic genetic markers are essential for linkage map construction and QTL mapping
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