Relationship Analysis Between MyoD1 Gene And Meat Quality Traits In Pig

Porcine myogenic differentiation genes (MyoD1) play a key role in growth and muscle development. Lots of other types of cell (such as fibroblasts, adipose cells) were transformed to myoblasts which were differentiated into mature muscle fibers. No report on the mutational sites in MyoD1 gene exon1 has been found in pig in domestic, and less report in abroad.The Analyzing the structure of MyoD1 gene, exploring its variation and researching on the influence of the variation loci with pork quality traits will provide a futher molecular basis for porcine meat quality improved.140 Duroc×Landrace×York hybrid pigs were random selected and slaughtered. Meat quality traits include drip loss, pH value flesh color shear force and IMF were measured by conventional method. Bioinformatical analysis was executed with the aid of the software and on line tools, include Bioedit, BLAST, SMART, ProtParam, SOPMA. SNPs of MyoD1 exon 1 were screened by PCR-SSCP technology. General linear model was used to analyze the relationship of genotypes and meat quality traits. Muscle fiber density, diameter, area, length, ratio of diameter and length diameter were measured based on the microscope observation of paraffin slides , and then the relationship of muscle histological characteristics and meat quality traits was analyzed.The different species of cluster graph showed the closest structure of the MyoD 1 gene in pig with cattle and sheep. A strong codon preference was found in MyoD1 gene. MyoD1 protein was consisted of BASIC (alkaline) domain, HLH domain, Pfam: Myf5 domain and 2 low complexity regions (LCR). The secondary structure was mainly composed of the random coil and the alpha helix. No suitable signal peptide was found in this protein. The phosphorylation sites were mainly found in Ser, Thr and Tyr. The G>A and C>T mutations were discovered respectively at 119 locus of the 5’ UTR and 387 locus of exon 1 which presented as AA and AB genotypes, and the AA in both loci was the dominant genotype in the population. The Hardy-Weinberg equilibrium state existed in the gene at the 2 loci. The mutations in 5 ’ UTR were significantly associated with muscle intramuscular fat content and pH value in pig (p < 0.05), but no significant correlation were found for meat quality traits in exon 1 (p < 0.05). Relationship Analysis between muscle fiber characteristics and meat quality traits showed that density were negative associated with shear force and marbling( p < 0.05 ), diameter and short diameter were positive associated with shear marbling( p < 0.05 ).The results indicate that the G>A mutation in 5’ UTR of MyoD1 gene are significantly associated with muscle IMF and pH value, the C>T mutation is synonymous mutations in the exon 1 of MyoD1 gene which no significantly associated with meat quality traits. The marbling is significantly associated with muscle fiber characteristics. The muscle fiber diameter, length to diameter, short diameter and area are increased by AA homozygous genotype of MyoD1 gene and density are reduced.