Identification of genes related to sexual maturation in Tibetan pig testis tissue based on transcriptome sequencing

【Objective】Based on transcriptome sequencing analysis， the genes related to sexual maturation were screened out in testicular tissue of Tibetan pigs so as to provide reference for improving the breeding performance of Tibetan pigs. 【Method】Tibetan boars before sexual maturity （2 months old） and after sexual maturity （24 months old） were selected as the study objects， testicular tissues of the Tibetan boars were collected by artificial castration method for transcriptomic sequencing， and differentially expressed genes （DEGs） were screened according to the criteria of false discovery rate （FDR）<0.05 and |log₂ Fold Change|>1. GO functional annotation analysis and KEGG signaling pathway enrichment analysis were combined to select the candidate genes related to sexual maturity in Tibetan boars. And the accuracy of transcriptome sequencing results were verified by real-time fluorescence quantitative PCR. 【Result】According to transcriptome sequencing， 5929 DEGs were screened from testicular tissue samples of Tibetan pigs before and after sexual maturity， among which 3822 DEGs were up-regulated and 2107 DEGs were down-regulated. The 5929 DEGs were selected to include spermatogenesis， ciliary motility， flagellate sperm motility， motile cilia， sperm mass， sperm apical sac， kinetic protein light chain binding， dynamic protein intermediate chain binding and other GO functional entries related to spermatogenesis and sperm motility. KEGG signaling pathway enrichment analysis showed that the DEGs was mainly enriched in receptor interaction pathway， axon-guided pathway， neural active ligand-receptor interaction pathway， calcium signaling pathway， etc. Based on the GO functional annotation analysis of DEGs and the enrichment analysis of KEGG signaling pathway， a total of nine genes related to sexual maturation in Tibetan boars were selected， which were BAX， DMRT1， FSHR， IGF1R， IZUMO1， LYZL4， LYZL6， SYCP3 and TNP2. Real-time fluorescence quantitative PCR detection results showed that the relative expression levels of the four genes， including BAX， DMRT1， FSHRand IGF1R， were decreased after sexual maturity compared with that before sexual maturity， all decreased by more than 50%. The relative expression levels of the five genes， including IZUMO1， LYZL4， LYZL6， SYCP3 and TNP2， were increased by 1.07-30.25 times compared with that before sexual maturity， and the increasing times of IZUMO1，LYZL4and LYZL6 genes reached extremely significant level（P<0.01）， which was basically consistent with the transcriptome sequencing results. 【Conclusion】Nine DEGs related to sexual maturity are detected in testicular tissue of Tibetan pigs before and after sexual maturity， namely BAX， DMRT1， FSHR， IGF1R， IZUMO1， LYZL4， LYZL6， SYCP3 and TNP2， which can be used as the main candidate genes to study the breeding ability of Tibetan pigs.