ABSTRACT
Insulin-like growth factorⅠ(IGF-Ⅰ) is essential for the growth and differentiation of hair follicles which is an important part of wool and cashmere.But there is no report on polymorphisms of the IGF-Ⅰ gene in cashmere goat,and also few candidate genes for cashmere production traits have been reported in cashmere goats.The objectives of this work were to detect the single nucleotide polymorphism(SNP) in the 5' flanking region of IGF-Ⅰ gene and to determine their association with fibre traits in Liaoning cashmere goats.The fibre traits data investigated in the experiment were combed cashmere weight,cashmere fibre length and cashmere fibre diameter.A few individuals of the Liaoning cashmere goats,selected according to phenotypic character,were used for SNPs detection in the 5'flanking region of IGF-Ⅰ gene,and four point mutation G→C(388 bp),A→G(668 bp),A→ C(719 bp),G→A(752 bp) were identified,which result in a CdxA bonding-site lack,and score increase of C/EBP site in the 5' flanking region compared with the wild type.Then different genotypes were detected in 520 Liaoning cashmere goats using create restriction site(CRS) and polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP),three genotypes,AA,AB and BB were observed coded for by two different alleles A and B for each SNP,and 13 diplotypes were identified in the groups of the four SNPs.The relationships between the genotypes and combed cashmere weight,cashmere fibre length and cashmere fibre diameter were analyzed.The statistical analysis showed that animals with the genotype AA of SNP2 in Liaoning cashmere goats had the thinnest cashmere fiber diameter compared with those with the AB and BB genotype(P