Identification of candidate genes associated with milk yield trait in buffaloes (Bubalus bubalis) by restriction-site-associated DNA sequencing

Abstract

The objectives of our present study included the screening of single nucleotide polymorphisms (SNP) that show significant differences in allelic frequencies between two buffalo populations (Egyptian and Chinese buffaloes), categorization of functional genes associated with these SNP by gene ontology, and pathway analyses to further understand their potential values as candidate genes closely associated with milk yield trait in buffaloes. In this study, double digest restrictionsite associated DNA sequencing was performed on Illumina HiSeq 2500 platform for 20 and 25 female buffaloes from Egypt and China, respectively. Approximately 118 Gb of sequencing data were obtained, and a total of 110,129 and 150,535 putative SNP were detected in Egyptian and Chinese buffaloes, respectively. Focused only on those SNP that differed significantly in allelic frequencies between the two populations, we found that genes associated with these SNP were significantly over-represented in the ionotropic glutamate receptor pathway, the endothelin signaling pathway, and the gonadotropin-releasing hormone receptor pathway, which contained a total of 29 genes. Of these, nine genes (ADCY5, CACNA1A, CREB1, INHBA, INHBB, PIK3R1, PLCB1, PRKCE, and SMAD2) participating in the hormonal regulation of lactation, were considered to be promising candidate genes worthy of further investigations for favorable alleles associated with milk yield. Our results provide useful information about genetic variations in Egyptian and Chinese buffaloes. The potential influences of nine candidate genes and their associated SNP on milk yield need to be validated in more buffalo populations.