Polymorphism of KIFI Gene Associated with Cashmere Traits in Xinjiang Goat Breeds

The wool fiber is structurally composed of low-sulfur proteins, for which the Keratin Intermediate-Filaments (KIF) gene is responsible along with Keratin-Associated Proteins (KAPs). In this study, PCR-RFLP and DNA sequencing were used to detect polymorphisms of the Keratin Intermediate-Filaments type I (KIFI) gene in three Chinese cashmere goat breeds (Xinjiang, Nanjiang and Bogeda White), to estimate gene and genotype frequencies and Polymorphism Information Content (PIC) and to determine impacts of genotype for KIFI on expression of cashmere traits. Results showed a novel A-C (GGCA-to-GGCC) mutation in intron 1, which forms a HaeIII endonuclease restriction site. Three unique PCR-RFLP banding patterns (genotypes AA, AC and CC) were found. The frequencies of the A allele in the samples from the goat breeds varied from 0.700-0.747. The genotypic distributions in three cashmere goat breeds were in Hardy-Weinberg equilibrium (p>0.05). According to the classification by PIC, the Xinjiang cashmere goat breed was more polymorphic at this locus than the other breeds. Furthermore, analysis of the impact of KIFI gene polymorphism on cashmere traits (cashmere fineness, down cashmere thickness, cashmere yield, body weight after combing) in goats from the Xinjiang breed indicated greater cashmere fineness in genotype AA compared to genotype CC (p<0.05), suggesting that this mutation may have significant influence on the cashmere fineness.