Study On Association Between Polymorphism Of DNAH2 And NDEL1 Genes With Meat Quality Traits In Pigs And Differential Expression Among Tissues

In this study, five pig breeds—Shaziling pig, Ningxiang pig, Taoyuan Black pig, Daweizi pig and exotic breed Large White pig were taken as object of research, and PCR-RELP method was applied to investigate the genetic polymorphism of genes DNAH2 and NDEL1, of which the gene frequency and genotype frequency were calculated. Then their association analysis with meat quality traits was conducted. In addition, Real-time Fluorescent Quantitative PCR approach was employed to analyze the differences in genetic expression of the two genes among different pig breeds and different tissue. The results are as follows:A Gâ†'C mutation of DNAH2 gene was discovered at-488 site through PCR-RELP and PCR sequence comparison. The PCR product was processed by restriction enzyme Pvuâ…¡ and genotyping was done. The results revealed that polymorphism existed in the pig breeds selected in our study. The analysis of association between different genotypes and meat quality showed that the backfat thickness and loin-eye area of GC genotype pigs were significantly different from those of GG genotype(P<0.05). The water loss rate of GG pigs was significantly higher than that of CC and GC pigs(P<0.05), and no significant difference was found for other meat quality genotypes. The expression level of DNAH2 gene among different pig breeds and tissue was determined by Real-time Fluorescent Quantitative PCR and results showed that the expression level of DNAH2 gene in Large White pig tissue was generally higher than that in the same tissue in Shaziling pigs, and the difference was very significant(P<0.01). And among different tissue of Large White pigs, the expression level of DNAH2 in spleen was the highest(1.38) and that in longissimus dorsi was the lowest(P<0.01). In all tissue of Shaziling pigs, the expression level of DNAH2 in longissimus dorsi was significantly lower than that in other tissue(P<0.01). The difference in DNAH2 expression level in caecum was very significant compared with that in leg muscle and spleen(P<0.01), and significant compared with that in lung and small intestine.The PCR product was processed by restriction enzyme Taq I, and polymorphism was found at-509Tâ†'C site of all pig breeds studied when NDEL1 gene was analyzed using PCR-RELP method. The assosiation between genotype and meat quality was investigated and the results indicated that the dressing percentage of CC individuals was significantly lower than those of TC and TT individuals(P<0.05). In terms of loin-eye area and water loss rate, TT genotype showed a significant difference compared with CC and TC individuals(P<0.05). No significant difference was shown in other genotypes relevant to meat quality. The results of Real-time Fluorescent Quantitative PCR indicated that the expression level of NDEL1 was significantly different from that from other tissue except liver(P<0.01). The genetic analysis of different tissue in Large White pigs showed that very significant difference in NDEL1 gene expression level was found between heart, pancrea, kidney, small intestine, and the expression levels in all the organs mentioned above were all very significantly different from others(P<0.01). In all tissue of Shaziling pigs, the expression level of NDEL1 gene in spleen and kidney was very significantly higher than other tissue(P<0.01), and very significant difference was also shown between kidney and spleen (P<0.01).