Transcriptome profile analysis identifies candidate genes for the melanin pigmentation of breast muscle in Muchuan black-boned chicken

Melanin-based coloration in the meat of black-boned chicken is a major economic issue in China. Variation in the pigmentation (hypopigmentation) of chicken muscle causes direct economic losses every year. To determine the molecular mechanisms involved in the melanogenesis of muscle tissue, this study used high-throughput sequencing to compare differences in the transcriptome between black (BM) and white (WM) chicken breast muscles. We constructed 6 cDNA libraries from BM and WM groups in Muchuan black-boned chickens. A comparison between the BM and WM groups revealed 264 differentially expressed genes, of which 152 were upregulated, whereas 112 were downregulated in black muscle. Gene ontology and a Kyoto Encyclopedia of Genes and Genomes pathway analysis identified several differentially enriched biological functions and processes of the 2 muscles. Seven promising candidate genes [PMEL, Ras-related protein RAB29, and 5 solute carrier superfamily genes: SLC6A9, SLC38A4, SLC22A5, SLC35F3, and SLC16A3] may play an important role in the melanogenesis of chicken muscle. Our data provide a valuable resource for identifying genes whose functions are critical for muscle melanogenesis, and will assist studies of the molecular mechanisms of melanogenesis regulation in chicken muscle.