Objective The interleukin 15 receptor subunit α (IL15RA) gene is an important part of the pro-inflammatory signaling of interleukin 15 (IL-15). Previous research showed that this gene was significantly differentially expressed in the longest back muscles of Fuqing and Nubian goats, which have extreme differences in growth traits, but the roles of the IL15RA gene in the growth and development of goats are not understood. In order to investigate the effects of this gene on growth traits in goats, this research aimed to establish the expressions profiles of IL15RA gene in Fuqing and Nubian goat group, as well as to identify the mutation sites and analyze the effects of polymorphisms on the growth traits of goats.

Methods Three 12-month-old wethers of each breed were randomly selected, and a total of nine tissues, including heart, liver, spleen, lung, kidney, head and neck semispinalis muscle, back longest muscle, thigh muscles and biceps brachii, were collected to construct the expressed spectrum of this gene in different tissues of the two breeds by qRT-PCR. As well as the DNA was extracted from Fuqing goat (n=108) and Nubian goat (n=286), PCR hybridization Sanger sequencing was to validate the SNP of IL15RA gene. genotypes were counted by PCR-RFLP method.The correlation with growth traits was analyzed.

Results (1).The expressed level of IL15RA gene in muscle tissues was highly significant lower than that in visceral tissues (P＜0.01), and its expression level in the back longest muscle tissues of Fuqing goats was significantly lower than that of Nubian goats (P＜0.05), and its expression in lung tissues was highly significant higher than that of Nubian goats (P＜0.01). One InDel site was existed in intron 3 of IL15RA gene of Fuqing and Nubian goats as g.22224_222225 Del A, Del22224. One SNP site was existed in intron 6 as g.33428A＞G.(3).SNP-g.33428 mutation was highly significantly relevance with body weight, chest circumference, chest width, hucklebone width of Fuqing goats (P＜0.01). (4). The haplotype combinations DD/AA and ID/GG were the superior haplotype combinations in Fuqing goats, and the haplotype combination ID/AA was the superior haplotype combination in Nubian goesats.

Conclusion IL15RA gene polymorphisms were significantly associated with growth traits in Fuqing and Nubian goats, and the IL15RA gene can be used as a candidate gene for the selection of growth traits in Fuqing and Nubian goats, so as to improve the efficiency of the seed selection of Fuqing and Nubian goats by combining conventional breeding with molecular markers-assisted selection.