Variation in the ovine KRT34 promoter region affects wool traits

Abstract

The hard α-keratins are the main component of wool fibre and are assembled in a highly organized fashion into the keratin intermediate filaments (KIFs). Variation in the keratins affects wool structure and fibre characteristics, and thus their genes make ideal candidates for the development of gene-markers. A total of 300 sheep were used for the variation study and 460 Merino × Southdown-cross lambs were used subsequently for the association study. The KRT34 promoter region was investigated using PCR-SSCP. Two different banding patterns (named variants A and B) were observed and a total of three SNPs (c.-435C/T, c.-364A/G and c.-323C/T) were identified in three different sheep breeds. Among the different breeds of sheep that were investigated, the overall frequencies of variants A and B were 37.88 % and 62.12 % respectively. The B variant was the most common in White Dorper sheep (94.83 %), when compared to the Merino (50.00 %) and New Zealand Romney (46.67 %) sheep. The two variants were also observed in the Merino × Southdown-cross lambs, where the presence of A appeared to be associated with decreased fibre diameter standard deviation (FDSD) (P = 0.030) and mean staple length (MSL) (P = 0.039). Associations with genotype were detected with mean fibre diameter (MFD) (P = 0.005) and FDSD (P = 0.008). These results suggest that variation in the KRT34 promoter fragment may affect MFD, FDSD and MSL, it could be a potential marker to improve wool quality.