Main wool color regulatory genes of Capra hircus and analysis of their pathways

【Objective】To explore dominant genes that regulated the wool color difference in Capra hircus and their pathways，so as to provide a theoretical basis for revealing the formation mechanism of characteristic wool color of the goat.【Method】 One-year-old male C.hircus goats were taken as research objects，and the skin tissue under the black wool on the shoulder and the skin tissue under white wool on the abdomen were collected respectively.The double strand cDNA was synthesized and purified with RNA as template，and then the cDNA library was constructed through PCR enrichment after processes such as end repair.Transcriptome sequencing was performed using Illumina HiSeq^TM 4000 sequencing platform.After filtering and quality control，differentially expressed genes（DEGs）were screened by DESeq2，and then GO function annotation analysis and KEGG pathway enrichment analysis were performed respectively.【Result】Compared with the white wool control group，there were 509 significantly up-regulated genes and 195 significantly down-regulated genes in the black wool test group，and 5 significantly（log₂ Fold Change>1，P_-adjust<0.05）up-regulated genes related to melanin production were filtered from 509 significantly up-regulated genes，including genes of tyrosinase（TYR），tyrosinerelated protein 1（TYRP1），melanocortin receptor 1（MC1R），keratin 19（KRT19）and keratin 79（KRT79）.The GO function annotation of significantly differential genes showed that the black wool test group was significantly enriched in melanosome，pigmentation，pigment biosynthetic process，melanin biosynthetic process，keratinocyte differentiation and other functions related to melanin formation.KEGG pathway analysis showed that，in black wool test group，the pathways closely related to melanin production were the tyrosinase metabolic pathway but not classical melanin production signal pathway such as Wnt/β-catenin，MAPK，PI3K/Akt or MC1R/α-MSH.【Conclusion】 TYR，TYRP1，MC1R and KTR19 genes are dominant genes regulating the wool color difference of C.hircus.Tyrosine metabolic pathway is the dominant pathway regulating the wool color difference of C.hircus.TYR，TYRP1，MC1R and KTR19 genes are up-regulated and activate the tyrosine metabolic pathway，resulting in the increase of melanin production，which is the major reason of color characteristics of black wool on the shoulder and abdominal white wool of C.hircus.