Integration of genomic methods for genotypes selection of pacu (Piaractus mesopotamicus) resistant to Aeromonas hydrophila bacteria

Author(s)

Vito Antonio Mastrochirico Filho

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2020-06-03.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2020-03-02
• Advisor: Diogo Teruo Hashimoto

Abstract

Pacu Piaractus mesopotamicus is considered one of the most important cultivated fish species from Brazil. Despite this representativeness, few genetic information is available for P. mesopotamicus, especially regarding disease resistance. Aeromonas hydrophila infection is responsible for major economic losses in P. mesopotamicus production. Challenge experiments have been performed to evaluate reliable estimates on selection of families genetically resistant to diseases. Therefore, the main objectives of this study were: 1) evaluate the resistance heritability in 36 P. mesopotamicus families subjected to A. hydrophila challenge; 2) characterize the genetic architecture identifying QTLs (Quantitative Trait Loci) related to A. hydrophila resistance by SNP sequencing / genotyping; 3) characterize genes belonging to immune system of individuals submitted to the disease resistance challenge, by transcriptome analysis (RNA-Seq). Moderate heritability values were found for survival rate and time of death, indicating that resistance against A. hydrophila in P. mesopotamicus can be improved by breeding programs. 17,453 SNPs were identified by RAD-Seq technique to investigate the genetic architecture of resistance to A. hydrophila. When a linkage map was constructed, the length of linkage groups (27 linkage groups) varied from 79.95 (LG 14) to 137.01 (LG 1) cM, with a total integrated map length of 2,755.60 cM. 22 QTLs in 17 LGs associated with A. hydrophila resistance suggested a polygenic resistance architecture affected by multiple loci with small additive genetic variance. With respect to RNA-Seq analyzes, 57 genes belonging to the pacu immune system were significantly expressed during the critical period of infection, while 23 genes were significantly expressed when mortality reached the plateau. The practice of integrating genomic methods for the application of breeding programs addressing pacu resistance to A. hydrophila infection is essential to accelerate national aquaculture production in a sustainable manner. (AU)

• FAPESP's process: 16/18294-9 - Integration of genomic methods for genotypes selection of pacu (Piaractus mesopotamicus) resistant to Aeromonas hydrophila bacteria
• Grantee: Vito Antonio Mastrochirico Filho
• Support Opportunities: Scholarships in Brazil - Doctorate