Genetic variation in the ovine KAP22-1 gene and its effect on wool traits in Egyptian sheep

Abstract

Abstract. The objective of this study was to investigate the genetic polymorphisms in the keratin-associated protein (KAP22-1) gene in Barki (n=206), Rahmani (n=28) and Ossimi (n=28) as the three major sheep breeds in Egypt. Subsequently, the detected variants were correlated with important wool traits. The traits included greasy fleece weight (GFW, g), staple length (SL, cm), prickle factor (PF, %), medullated fiber (MF, %), fiber diameter (FD, µm), crimp percentage (CR, %) and the standard deviation of FD (SDfd, µm), as well as the subjectively assessed traits of kemp score (KS), handle grade (HG), greasy color grade (GCG), bulk grade (BG), luster grade (LG) and staple structure (SST). Animals were genotyped by polymerase chain reaction (PCR) – single strand conformation polymorphism (SSCP). Five SSCP banding patterns representing three different nucleotide variants (A, B and C) were detected. DNA sequencing confirmed three single nucleotide polymorphisms (SNPs). Animal age significantly affected GFW (P=0.007), SDfd (P=0.006), SL (P=0.002), CR (P=0.006), KS (P=0.001), LG (P=0.006) and SST (P=0.013). Likewise, the breed had a significant effect on all studied traits except HG and BG, which was not significant. Results showed significant associations between the KAP22-1 variants and CR (P=0.01), SL (P=0.012), KS (P<0.001) and GCG (P=0.01). Interestingly, animals with BB genotypes tended to produce more wool yield (1163.63±65.91 g) with high SL (8.38±0.20 cm), CR (8.38±0.21 %) and KS (1.98±1.88). Results of this study strongly recommend the KAP22-1 gene as a candidate gene for wool production traits in Egyptian sheep, with new useful insights into the visually assessed wool traits. The identified genetic markers may be incorporated into breeding strategies and genetic improvement programs of wool traits in Egyptian sheep.

Identification of the Keratin-Associated Protein 22-2 Gene in the Capra hircus and Association of Its Variation with Cashmere Traits

“…Variation in KRTAP7-1 was found to affect wool yield in sheep [25] and variation in KRTAP6-3 was found to affect fiber diameter [26]; variation in sheep KRTAP8-1 affects the mean staple length of wool fibers [27]. KAP22-1 gene variation in sheep affects wool curvature [28]. A negative correlation between KAP13-1 gene variation and fiber traits has been found in Changtang goat populations [29].…”

Ovine KRT81 Variants and Their Influence on Selected Wool Traits of Commercial Value

“…The finding that variation in ovine KRT81 affects the two related fleece weight traits, without impacting staple length and fibre diameter traits has not been observed for other KRTs and KRTAPs . For example, variation in KRT31 [ 6 ], KRTAP1-2 [ 23 ] and KRTAP20-1 [ 24 ] affects fleece weight traits, but also other traits like MSL and/or the fibre diameter traits, like MFD, FDSD and CVFD. The absence of an effect on MSL or fibre diameter traits leaves three things that may affect the weight of the fleece: variation in the density of the individual fibres, variation in the number of wool follicles per unit area of skin, or variation in the amount of skin that contains follicles, the latter suggesting KRT81 is in some way affecting the skin, not just the wool follicles therein.…”

New Insights into Polymorphisms in Candidate Genes Associated with Incidence of Postparturient Endometritis in Ossimi Sheep (Ovis aries)

“…Ossimi is a prominent sheep breed in Egypt, which supplies around 6% of the nation's total production of red meat [3]. They are found across Egypt, particularly in the northern Nile Delta and along the western Mediterranean coast [4]. They are tiny to medium-sized with a fat tail and coarse wool.…”