The selection of individuals with improved performance for immunological responses contributes for a sustainable aquaculture. However, the development of genetic basis for breeding programs directed to species of fish from Brazil is still scarce. Infection caused by Aeromonas hydrophila has been responsible for about 20 to 30% of the mortality rates for pacu (Piaractus mesopotamicus), one of the most important native species from brazilian aquaculture. Bulk segregant RNA-Seq (BSR-Seq) analysis has provided identification of SNP (Single Nucleotide Polymorphism) markers associated with resistant and susceptible phenotypes of challenged individuals by pathogenic organisms, which may be responsible for variations in the resistance of farming families of fish submitted to infections. Mapping of quantitative trait loci (QTLs) achieved by genome wide association studies (GWAS), have enabled the dissection of genetic variability, and the identification of genomic regions involved in the control of disease resistance traits. The objective of this study is to characterize, using the BSR-Seq technique, SNPs located in disease-associated differentially expressed genes, after A. hydrophila infection in pacu, and which are possibly related to the extreme phenotypes of challenged families by Aeromonas septicemia. Subsequently, SNPs significantly associated with resistance phenotypes will be corroborated by GWAS analysis, using genotyping data from a dense array of SNPs, previously developed for this fish species. SNPs will be considered really associated with resistance against A. hydrophila when they are detected in both BSR-Seq and GWAS analyzes. The results will achieve a high-resolution mapping of potential genomic regions (QTLs) linked in the resistance to A. hydrophila infection of pacu.
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