| Longissimus dorsi (LD) in swine (12 groups includes Shanzhu, Landrace, Yorkshire and other breeds) were used to study the polymorphism of meat quality target gene VDR and PPARy2 via PCR-RFLP and sequencing technology. We want to explain the association of gene polymorphism with meat quality traits and set the mathematic model:GLM to analyze the relationship between non-countable variable genotype) and countable variable (meat quality traits).Meat quality in 12 groups found that the mean shear force of fresh meat in LD was 2.40±0.71 (Kg-fN). The shear force of Shanzhu was the lowest,2.00±0.57 (Kg-fN, P<0.05), while there was no significant difference in other breeds. The results of marbling score showed that the average of 12 groups was 2.67±0.74, Shanzhu was the highest (3.75±0.35, P<0.01) and Duroc×Shennong was the lowest (1.82±0.60). We also found that the IMF of 12 groups was between 1.5% and 4%. IMF of different groups had a big difference. The highest was in YorkshireShennong (3.40%±1.25%, P<0.05), the second was in Berkshire (2.98%±0.47%). IMF was the lowest in PietrainxShennong and Shennong, respectively. Marbling score and IMF in LD of 12 groups were similar trend.VDR gene showed that it could be expressed in all of LD in the 12 groups. The mean expression of VDR was 0.76±0.08. The VDR’s expression was increased with the increase of LD shear force. Their relationship could be 0.22 (Y=1.84X+0.902, R= 0.22). The polymorphism of Fokl which was in the second promoter of VDR showed that Twas replaced by C in the fragment (GGATG). It caused wild f type mutated to F type. Among the 101 pigs, the proportion of F, Ff and f type was 41.58%、36.63% and 21.78%, respectively. There were three genotypes of this locus in Shanzhu LD. There was no f type in Landrace and Yorkshire with high expression of F type. And VDR Fokl genotypes changed a lot in Shennong and Shanzhu crossbred:f and Ff type increased significantly with F type decreasing. GLM model was used to analyze the association of genotypes with LD shear force in which genotypes was as a major factor. Compared to genotypes difference, it was found that f and F type affected the meat shear force extremely significant (P<0.01). It suggested that polymorphism of VDR Fokl was a major factor for myo-protein synthesis.PPARy2 gene showed that the low expression was in LD of all the 12 groups. The mean relative expression was between 0.35±0.07-0.58±0.07. This gene in Berkshire was higher than other breeds (P<0.01). The Bsrl polymorphism was A/G in CCAGT changing into CCAAT so that b type mutated to B type. The proportion of B, Bb and b type was 54.46%,33.66% and 11.88%. There were three genotypes in Shanzhu Bsrl locus; the b type decreased in its two-crossed while b type was missing in its three-crossed. At the same time there was no b type in Landrace and Yorkshire. Landrace had B type only. However, Bb type was highly expressed in Shennong except B type. Bb type was also high in Shennong’s two or three-crossed. GLM model was set to analyze the association of PPARy2 genotypes, as major factor, with meat quality traits. LD marbling, IMF and shear force in different genotypes was different significantly (P<0.05). The high expression of b type was good for adipose proliferation so as to maintain appropriate meat tenderness. It suggested PPARy2 gene could be the quality meat target gene for lipid metabolism in muscle. |
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