The Relationship Between Target Genes And Meat Quality In Shanzhu Crossbreds

To aim at good genes of meat quatily in Shanzhu,1/2or1/4crossbreds at the age of9-10months were used to study their meat characteristics and5key target genes.1Meat quality improving in Shanzhu crossbredsThe results were showed that the evaluation of meat quality was normal and very good. It was found that the score of meat color was range from3to4with kindly fresh reddish and marbling score was also reasonable in1/2or1/4crossbreds. Comparing meat tenderness in longissimus muscle (LD), females with higher intramuscular fat (IMF) were better than males (P<0.05) whether1/2or1/4crossbreds not, due to females DL contained higher IMF content (P<0.05). In the future, free fatty acids (FFA) in IMF were analysed. FFA ratio was divided into37%-39%saturated fatty acids, nearly50%monounsaturated fatty acids and10%polysaturated fatty acids. The level of cis-oleic acid (C18:1) was the highest in all of them.2PCR optimal conditions of5key target genesFive of RARa, PPARy, VDR, RYR1and PRKAG3were selected the key target genes. Three primers (PPARγ、RYR1and PRKAG3) of them were designed, while the primers of RARa and VDR were referent from other study, to use in our research.Three factors of annealing temperature, Mg2+concentration ([Mg2+]) and number of cycles in PCR reaction were selected to study the PCR working conditions. The results were that PCR optimal conditions in5key target genes were different, such as59℃,1.5mmol [Mg2+] and38cycles were for RARα,59℃,2.0mmol [Mg2+] and35cycles were for VDR,62℃,2.5mmol [Mg2+] and41cycles were for PPARγ,57℃,0.5mmol [Mg2+] and35cycles were for RYR1, while57℉,1.0mmol [Mg2+] and41cycles were for PRKAG3, respectively.3Expression of5key target genes by qRT-PCRThe results were showed that expression of RARa mRNA was lowest in1/4female crossbreds (P<0.05), VDR mRNA of1/2and1/4female crossbreds was higher than that of1/4males (P<0.05, P<0.01), but RYR1mRNA of females was higher than that of males (P<0.05), significantly. While, PRKAG3mRNA and PPARy mRNA was at the same level among three crossbreds.4The relationship between5key target genes and meat qualityThree regression equations were set up as1) IMF with PPARy and C18:0,2)pH24 value with RYR1and PRKAG3,3) Water loss rate with RYR1and PRKAG3, respectively.1) YIMF=51.27-2.82X1-2.25X2-0.28X12+0.06X22+0.07X1X2(X1:PPARγ, X2:oleic acid, R0.7099, P<0.05).2) YpH24=5.82+0.07X1+0.05X2-0.01X12-0.0008X22-0.005X1X2(X1:RYR1, X2:PRKAG3, R0.6599,P<0.05).3) Ywater loss rate=16.62+5.83X1+2.01X2-0.41X,2-0.15X22-0.47X1X2(X1:RYR1, X2:PRKAG3, R0.6384, P<0.05).As summing, RYR1and PRKAG3could be upstream regulatory genes for the skeletal muscle pH and water loss rate, three of RARa VDR, PPARy and PPARy the key effects on fat metabolism in skeletal muscle, VDR also might be one of key genes for pork tenderness.