Genetic Characteristics Of Pork Quality Traits Mainly Related Gene And Its Role And Influence On Meat Quality

Pork is one of the most important meats in our country. With the development of swine industry and improvement of people’s life, the requirments of meat quality rise year by year, so the improvement of meat quality has become the largest challenge in pig production. Meat quality is a complex economical trait which affected by a lot of factors, but the regulatory mechanism of micro-effect polygenes determines porcine meat quality, carcass characteristics and other relative quantitative traits, In this study, we selected candidate genes associated with meat quality by candidate gene approach to detect molecular markers in pigs, and used qRT-PCR to examine the expression differences of candidate genes associated with carcass and meat quality in M.longissimus dor si muscle of crossbred pigs. The objective of this study was to investigate the effects of polymorphisms in ten candidate genes and their expression as well as genders and bloodlines on carcass and meat quality traits in pigs.We tested the polymorphism of17candidate genes, and investigated19single nucleotide polymorphisms (SNPs) among10genes. The genotype frequency and allele frequency for differences of genotype distributions were calculated for each polymorphism of nine meat quality related genes in different pig breeds. Except for MYF5, the genotypic and allelic frequencies of the remaining genes exhibited high rates of polymorphisms, and a x2test revealed that differences in the genotypic frequencies were very significant (p<0.Ol) or significant (p<0.05) in different pig breeds. Genotype distributions didn’t show significant (p>0.05) differences in two genders. Genotype distributions of MYOD1and LPL showed significant (p<0.05) differences in two bloodlines. The analysis revealed that MC4R C.1426A allele, LEPR c.232T allele, HSL c.442A allele, MYF5c.1205A allele, MYOD1c.510C, H-FABP c.1322T and ADRB3c.l192A were dominant in shanzhu pigs. An association analysis revealed that all polymorphic markers tested, with the exception of MYOD1gene, showed very significant (p<0.01) or significant (p<0.05) associations with aspects of carcass and meat quality traits in crossbred pigs. Each allele’s main effects were as follows:MC4R c.1426A allele increased body weight and fat deposition. LEPR c.232A allele increased water-holding capacity. HSL c.442G allele increased rib eye area and decreased intramuscular fat (IMF). LPL c.114T allele increased IMF and yellowness and LPL c.114C allele increased rib eye area and water-holding capacity. MYF5c.1205A allele improved tenderness and water-holding capacity. ADRB3 c.1192G allele increased IMF. H-FABP c.1322T allele improved tenderness and IMF. PPARγ c.175G allele increased water-holding capacity.We used qRT-PCR to examine the expression differences of11candidate genes in M.longissimus dorsi muscle of crossbred pigs. The expression of LEPR, PPARa, ADRB3, AdPLA, SCD and LPL showed significant (p<0.05) differences between two crossbreds respectively. PPARa and ADRB3showed significant (p<0.05) differences in two genders respectively. Variance analysis (ANOVA) revealed that expression differences among different genotypes of LEPR, LPL, MYF5, PPARy and ADRB3genes were significant (p<0.05). LEPR AT genotype was better for gene expression than AA or TT genotype. PPARy AG genotype was better for gene expression than AA or GG genotype. ADRB3AG genotype decreased gene expression. LPL c.114T allele increased gene expression. MYOD1c.510A increased gene expression. An association analysis revealed that expression differences of candidate genes, with the exception of PEPCK gene, showed very significant (p<0.01) or significant (p<0.05) associations with aspects of carcass and meat quality traits in M.longissimus dorsi muscle of crossbred pigs. MC4R, LEPR, LPL and PPARa expression increased body fat content and intramuscular fat content. MYF5expression increased lipid deposition but decreased lean meat percentage and tenderness. MYOD1expression increased pH24value. ADRB3expression improved carcass traits. PPARy expression decreased carcass quality and tenderness. AdPLA expression increased intramuscular fat content but decreased protein content. SCD expression increased intramuscular fat content and tenderness.These results highlight some alleles or genotypes for porcine carcass and meat quality traits, develop rapid and simple detective methods for these alleles or genotypes, analysis the effects of these genes’ SNPs and expression on carcass and meat quality traits, and provide some data for the evaluation and utilization of meat quality related gene in the effort to improve pigs’meat quality.