Goat SPEF2: Expression profile, indel variants identification and association analysis with litter size.

SPEF2 (sperm flagella 2 gene), also known as KPL2, plays important roles in germ cell development. The aim of this study was to investigate the mRNA expression profiles of goat SPEF2 among different tissues, as well as the relationship between SPEF2 indel polymorphisms and reproductive traits of 1104 Shaanbei white cashmere (SBWC) goats, and fully explore the expression characteristics and genetic effects of goat SPEF2. Results showed that SPEF2 was widely expressed and presented dynamic changes in goat testis at different developmental stages. SPEF2 mRNA expression level during meiosis phase was approximately equal to that during mitosis phase. Additionally, three potential insertion/deletion (indel) mutations were tested and verified by PCR and sequencing methods among 14 potential indel variant which are related to reproduction traits. For L-8 (NC_030827.1:g.38459098_38459107delTCAGTTCAGT: rs644277083), association test revealed that the goats with heterozygous ID had significantly more lambs than those with homozygous type II (P < 0.05). The influences of joint genotypes of L-8 and L-1 (NC_030827.1:g.38527458_38527459insGTTCACACCCAGTT) on goat reproductive traits were significant (P < 0.05). The association between combined genotypes and litter size showed that goats with homozygous genotypes had larger litter size than that of any of the other genotypes. Furthermore, through bioinformatics analysis, the remarkable influence of indel L-8 on traits might be caused by the change in AR (androgen receptor) binding site. These preliminary results are helpful to comprehensively study the function of SPEF2 and to provide theoretical references for SBWC goats breeding.