Efeito do cromossomo x no mapeamento de regiões genômicas sobre características de interesse econômico em búfalos da raça murrah

Abstract

The X chromosome is the fifth largest chromosome in the buffalo genome, containing many genes that can influence the expression of economically important traits. However, in current GWAS studies, researchers almost exclusively use molecular markers from autosomes, excluding the sex chromosomes. Thus, the aim of this work was to identify potential candidate genes in a Genome-Wide Association Study (GWAS) on the X chromosome related to reproductive traits (age at first calving – AFC, first calving interval – CFI1, and second calving interval – CFI2) in Murrah buffaloes. CFI1 represents the period from an animal's calving to the subsequent one during its first lactation, while CFI2 refers to the interval between the second and third subsequent calving during the second lactation of the animal. Phenotypic information from 3,913, 1,096, and 743 animals was used for AFC, CFI1, and CFI2, respectively. The pedigree included 96,897 animals, of which 1,222 were genotyped using the 90K Axiom® Buffalo Genotyping Array (Affymetrix/Thermo Fisher Scientific). The weighted single-step methodology (WssGBLUP) was employed, selecting windows that explained more than 0.5% of the additive genetic variance with 100 adjacent SNPs. Gene ontology analysis was exclusively conducted on significant windows of the X chromosome. Genes with potential functions in sexual precocity and reproductive efficiency emerged as candidates for AFC (POF1B and DACH2), CFI1 (AR and SLC6A14), and CFI2 (RPS6KA6, PCDH11X, PABPC5, G6PD, GDI1, RPL10, FLNA, MECP2, and L1CAM). This study provided greater insight into the strong association of X chromosome markers with reproductive traits in females, and these findings may contribute to understanding economically relevant biological processes in buffalo species.