Abstract
Simple SummaryOver the last decades, many genetic tools have been developed in order to improve our knowledge and understanding of the links between physiology and genetics. In our research, European Sea Bass was selected in order to study stress response physiological indicators in relation to growth and disease resistance. Therefore, DNA samples were collected in order to identify any potential relation between the aforementioned traits and their genetic component. Genomic areas related to body weight and stress response were detected. No genomic areas related to disease resistance were identified. Based on the results, fish that hold the genetic information for increased body weight and improved stress response could be used for genetic improvement purposes.There is a growing interest in selective breeding in European sea bass (Dicentrarchus labrax), especially regarding family selection based on growth performance. In particular, quantitative trait loci (QTL) identification in sea bass enhances the application of marker-assisted breeding for the genetic improvement of the production traits. The aims of the study were to identify potential QTL affecting stress and immunological indicators, body weight, and mortality after vibriosis injection in sea bass as well as to estimate heritability and genetic/phenotypic correlations for the aforementioned traits. To this end, stress test was performed on 960 offspring and a sub-group of them (420) was selected to explore the mortality after vibrio injection. Selective genotyping was performed in 620 offspring for 35 microsatellite markers and distributed into 6 linkage groups. The length of the genetic linkage map was 283.6 cM and the mean distance between the markers was 8.1 cM. QTL affecting body weight in three different growth periods detected on linkage groups LG1, LG4, LG6, and LG14. A QTL associated with weight in early growth stages (290–306 days post-hatching) was also identified on LG3. QTL analysis confirmed the existence of QTL affecting cortisol levels, on LG3 and LG14. Moreover, new QTL affecting only cortisol and glucose levels were detected on LG1 and LG23. No QTL affecting hormonal or biochemical marks was found on LG4 and LG6. Heritability of cortisol, lysozyme levels, and mortality were high (0.36, 0.55, and 0.38, respectively).
Highlights
Quantitative genetic variation characterizes many traits of economic importance in livestock and welfare of farmed animals
Selective breeding is still relatively limited in few aquaculture species and the majority of breeding programs is based on family selection despite the extensive availability of molecular genetic tools for many different fish species [6,7]
The analysis indicated putative quantitative trait loci (QTL) positions and provided estimated effects and in the second case, the polygenic component was included in the analysis of the putative
Summary
Quantitative genetic variation characterizes many traits of economic importance in livestock and welfare of farmed animals. Variation in such complex traits is often influenced by a number of different quantitative trait loci (QTL), as well as environmental factors. QTL identification in commercially important species promotes the application of marker-assisted breeding for the genetic improvement of production traits. Selective breeding is still relatively limited in few aquaculture species and the majority of breeding programs is based on family selection despite the extensive availability of molecular genetic tools for many different fish species [6,7]
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