Detecção de assinaturas de seleção em zebuínos provenientes do Brasil e Continente Asiático

Abstract

From technological advances in the area of genomics and bioinformatics, it became possible to study the genetic structure of breeds and understand the changes in the genome caused by the process of natural and artificial selection over the generations. Thus, the objective of this study was to identify selection signatures in Nelore, Gir, and Sindhi cattle from Brazil and Asian continent. The genotypes used, from Brazil, consisted of 173 Nelore animals, 48 Gir animals, and 49 Sindhi animals. The genotypes from the Asian continent, from India, were composed of 50 Nelore animals and 27 Gir animals, while nine Sindhi animals were from Pakistan. All animals were genotyped with the high-density Illumina BovineHD BeadChip panel. For the detection of selection signatures, the XP-EHH, Rsb, and Fst methods were used. To define the selection signature regions, the window approach considering the size of 50kb was used. In each 50kb window, the average was obtained for each of the three methodologies studied. Therefore, the 40 windows of the highest average (for the three methods) for each breed were considered for gene identification and functional analysis. In this study, it was possible to observe selection signatures between populations of the same breed, but differing in terms of geographic location. Both Brazil and Asian continent differ in selection pressures and objectives. Thus, the identified selection signatures demonstrate how animal breeding programs are able to shape the genetic constitution of these breeds so that they are in conformity with the production systems. The identification of genes mainly related to adaptability (EIF2AK4, CPVL, RAP1GAP, HDHD3, BUB1B, U1, FILIP1L, SHANK2), immunity (FCGRT, ITGA6, MEIS1, BCL2L12), and resistance to pathogens and parasites (TREML1 e TREM2) indicate that, even if these traits were already present in the first imported zebu cattle, certain alleles were fixed so that Nelore, Gir and Sindhi animals could adapt to the Brazilian production conditions.