Identification and Analysis of Genes Related to Testicular Size in 14-Day-Old Piglets

Simple Summary The reproductive performance of pigs can vary due to the influence of genetic factors, and this is aggravated by environmental factors. Multiple complex factors affect the difference in the reproductive performance of boars in adulthood. This study examined those genetic differences in young piglets, at a time when they are less affected by the environment. Testicular tissue samples were used to explore candidate genes and related pathways affecting testicular size during early development. This experiment into the reproductive performance of pig breeds using the RNA-Seq analysis of testicular tissue with early developmental differences can provide a theoretical basis for breeding by determining key candidate genes that control testicular predevelopment. The data will be used for subsequent research into the genetic mechanism of boars, which is important for early breeding and improvement.Abstract The RNA-Seq technology was used to screen the key genes that affect the early development of the testes of Duroc x Landrace x Yorkshire piglets, to determine the regulatory pathway and provide reference for subsequent reproductive performance research, breeding, and other production practices. This study selected 14-day-old Duroc x Landrace x Yorkshire piglets as the trial animals. Testes from piglets with similar weights and no pathological changes were divided into small testis (ST) and large testis (LT) groups, and the RNA-Seq screening of differentially expressed genes (DEGs) was performed to find candidate genes and regulatory pathways related to early testicular development. The results show that 570 DEGs were found in the ST and LT groups, with 281 upregulated and 289 downregulated. The DEGs were mainly enriched on 47 gene ontology (GO) functional items. The Kyoto encyclopedia of genes and genotypes (KEGG) enrichment analysis found that there were 44 significantly enriched KEGG signal pathways, and the regulation of testicular development mainly focused on the arachidonic acid metabolism, Wnt signaling pathway and GnRH secretion pathways. The PTGES, SFRP1, SPP1, PLA2G4E, KCNJ5, PTGS2, and HCN1 genes were found to be as closely related to the testicular development of these Duroc x Landrace x Yorkshire piglets, and the differential gene expression was consistent with the real-time quantitative reverse transcription PCR (real-time qRT-PCR) validation results. This study was validated by high-throughput sequencing analysis and real-time qRT-PCR, and showed that the PTGES, SFRP1, SPP1, PLA2G4E, KCNJ5, PTGS2, and HCN1 genes may be involved in the regulation of germ cell development, spermatogenesis and semen traits. These should be further studied as candidate genes for early testicular development and reproductive trait regulation in boars.