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Association of Variation in the Ovine KAP1.1, KAP1.3 and K33 Genes with Wool Traits

Theopoline Itenge, Jon Hickford, Rachel Forrest, Grant McKenzie, Chris Frampton

Abstract


\"A candidate gene approach was used to identify genes that may be associated with wool traits in Merino and Merino-cross sheep. Polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis was used to identify sequence variation in the Keratin-Associated Protein (KAP) 1.3 and Keratin Intermediate-Filament protein (KRT) K33 genes (KAP1.3 and K33 respectively), while agarose gel electrophoresis was used to detect length variation in the KAP1.1 gene (KAP1.1). Two half-sib families (SL1, n = 131 and SL2, n = 35) were created for analysis. Wool samples were collected from the mid-side region of the SL1 progeny at 12, 24 and 36 months of age, and the SL2 progeny at 12 months of age. These samples were measured for a variety of commonly assessed wool traits.

The genotype of the sire used in SL1 was AB, BD and AB for KAP1.1, KAP1.3 and K33 respectively, while the sire used in SL2 was BC, CJ and DE.

In SL1, inheritance of KAP1.1 A was associated (P = 0.036) with a higher yield at 24 months of age compared to the KAP1.1 B. The same trend was also observed for yield at 36 months (P = 0.078). KAP1.3 B was associated (P = 0.045) with whiter wool at 36 months of age compared to the KAP1.3 D. Inheritance of the SL1 K33 B was associated (P = 0.038) with a smaller fibre diameter standard deviation compared to the SL1 K33 A at 12 months of age and it was also associated (P = 0.023) with an increase in mean staple strength compared to the SL1 K33 A at the same age. At 36 months of age, the K33 A was associated (P = 0.019) with whiter wool compared to the K33 B in SL1.

In SL2, inheritance of KAP1.1 B was associated (P = 0.006) with increased mean staple length compared to the KAP1.1 C and tended to be associated (P = 0.074) with a decrease in wool brightness compared to the inheritance of the KAP1.1 C. Inheritance of KAP1.3 J allele was associated (P = 0.011) with increased staple length compared with the inheritance of KAP1.3 C and was also associated (P = 0.036) with a decrease in wool brightness when compared with the inheritance of the KAP1.3 C. The inheritance of K33 D was associated with longer staple length (P = 0.029) and tended to be associated with a decrease in wool brightness (P = 0.056) compared to the inheritance of K33 E.

Although a narrow study, these results suggest that variation in the genes coding for the KRTs and KAPs have the potential to impact on wool quality and that further investigation of them would be warranted.\"

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