Estudo das características morfométricas e da associação genômica Ampla (GWAS) em equinos da raça Campolina

Abstract

Studies in morphometric analyzes of horses have progressed in recent years; always assuming this assessment is related to the horse's fitness. With the advance of genetic evaluation in equine culture, the opportunity has been created to obtain precise information about the functionality of the animals, as well as greater accuracy of offspring and to obtain the desired allele. This research aims to study the Phenotypic characteristics and the Genomic Wide Association Study (GWAS) of morphometric measurements in Campolina horses. A total of 267 horses, aged over 36 months, registered at the Brazilian Association of Horse Breeders Campolina (ABCCCampolina), belonging to the states of Bahia, Rio de Janeiro and Minas Gerais, were measured for the Phenotypic analysis of 45 morphometric measurements. From these horses, 48 animals were selected, based on the pedigree, for DNA extraction for subsequent GWAS performance. And, to carry out the GWAS, data from 18,876 genealogical records of ABCCCampolina were used, which contains information from 15 morphometric measurements. Genomic DNA was extracted from hair bulb samples using the Nucleospin Tissue kit. After DNA extraction, DNA genotyping was performed using the GGP Equine Illumina ~65000SNP chip. Statistical analyzes performed for phenotypic data were Pearson correlation, covariance, discriminant analysis and principal components. Afterwards, genotypic analysis and GWAS were performed. Analyzes were performed using Excel®, RStudio® and BLUPF90®. In the Pearson correlation analysis, it was observed that the linear and perimeter measurements correlated positively with the 45 morphometric measurements. Most angular measurements had non-significant correlations with morphometric measurements. It was found that in the analysis of covariance, principal components and discriminant that males presented less variation in linear and perimeter measurements than females. Males were taller and had wider chest, greater scapulohumeral angle and larger neck, both in length and perimeter than females (P<0.05). Females had greater thoracic perimeter, wider hips and greater opening of the thigh-ground and femoro-tibial angles than males (P<0.05). In the GWAS analysis, it was observed that for the 15 morphometric measurements, 628 SNPs were responsible for explaining more than 1% of the genetic variation that occurred in Campolina horses. It is concluded that in Campolina breed, linear and perimeter measurements are the most suitable morphometric measurements for classifying horses according to gender, with greater sexual dimorphism when compared to angular measurements. Possible candidate genes for the morphometric measurements evaluated were: RBMS3, HAUS, PIK3R1, SUCLG2, ZCWPW2, CLYBL, DNAJC3, DNAJC15, KMO, LMOD3, LOC100630169, LOC102148584, LRCH1 and THRB.