Association tests on linked-QTL region of chicken chromosome 1

Author(s)

Dênia Borges Attilio

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2014-04-14

Examining board members

Millor Fernandes do Rosário; Luiz Lehmann Coutinho; Danisio Prado Munari

• Advisor: Millor Fernandes do Rosário

Abstract

Actually, Brazil is considered the world\'s first- and third-biggest exporter and producer of poultry meat, respectively. These performances are mainly consequence of animal breeding based on the estimation of breeding value combining phenotypes and pedigree information. However, usually the selection is not carried out for each trait separately due to genetic correlation between them. This correlation is caused by pleiotropy or linkage. We aimed to detect associations between phenotypic traits of interest to poultry industry and SNPs on a region of chromosome 1 (168 - 208 cM and 57 - 71 Mbp), where putative linked-QTL were previously mapped. A chicken 60k SNP BeadChip was used to genotype 14 animals from Parental generation (TT males and CC females) and 28 F1 of the TCTC population that was developed by Embrapa Swine and Poultry. The TT line showed greater genotypic variability than CC, however, F1 were higher than Parental generation based on the number of heterozygotes and MAF. The polymorphism more frequent in both generations was the transitions with 84.3%. The 144 most informative SNPs were selected based on heterozygosity of the five F1 couples which generated the 453 F2. There was a reduction of heterozygotes and MAF in F2, based on the F1 mean value, as consequence of some degree of relationship and inbreeding between animals that formed this generation. Haplotype blocks demonstrated that the TT males showed 25 blocks, CC female (17) F1 (32) and F2 (23) with an average size of 278, 467, 242 and 160 kbp, respectively. It was observed that 236 (42.7%) phenotypic correlations were significant. Out of these, the highest number was found between PB_MS and other 17 traits and the highest estimated value was between PB_MS and EE_MS (-0.90). Out of 3,456 expected association tests, 609 (17.6 %) were considered significant (p < 0.05), being 424 (69.6%) with additive effect and 185 with dominance effect (30.4%). PV41 presented the highest number of associations (123), while DOR was not associated to any SNP. Proportionally, the highest number of SNPs was associated close to the pleiotropic QTL 2 with 17 traits. On the other hand, the highest significance levels (p < 9.59 x 10-8) for the additive effect were evidenced for SNPs located close to the pleiotropic QTL 1 and associated only with PV41 (Gga_rs13869715 (A < C), Gga_rs13870613 (T < C), Gga_rs14827719 (A < G), GGaluGA019336 (T < C) and GGaluGA019533 (A < C)). Novel associations were detected for GP3541, CA3541, INT, PES, CAB, FIG, COR, MOE, PUL, HEM, COL, TRI, TC, PB_MS, EE_MS, CZ_MS when we compared our results with literature. Finally, putative positional and functional candidate genes were indicated such as IGF1, MYBPC1, MTPN, SOX-5, FGFR1OP2 and TTLL12, which may be used in gene expression analysis. (AU)

• FAPESP's process: 12/03941-8 - Association tests on linked-QTL region of chicken chromosome 1
• Grantee: Dênia Borges Attílio
• Support Opportunities: Scholarships in Brazil - Master