A relationship between the polymorphism in the coding and 5' regions of the porcine MyoD genes and microstructure traits of longissimus lumborum muscle

The MyoD family consists of four structurally related genes, products of which control the processes of myogenesis. The objective of the study was to analyse the relations existing between selected polymorphisms in the coding and 5’ flanking regions of the porcine MYOD1, MYF5 and MYOG genes and microstructure of longissimus lumborum (LL) muscle. Torhyb Line [(Polish Large White × Polish Landrace) × Pietrain] fatteners were used (n=115). The diameter (µm) and content (%) of slow-twitch oxidative (STO), fast-twitch oxidative (FTO), fast-twitch glycolytic (FTG) and pathological fibres was determined. The relation between MyoD genotypes and microstructure characteristics was analysed in a group of 93 fatteners of the CC or CT genotype at locus RYR1. The pigs of TT genotype at RYR1 locus were excluded due to significant effect identified of that genotype on the muscle microstructure. Sex appeared to have no significant effect on the muscle microstructure traits. The significant effect on LL microstructure was identified regarding the locus MYOD1. The C489T transition affected the diameter of FTO fibres, and the transversion G566C affected the content of fibres FTO and FTG in a bundle. The mutation G566C may be interesting for further studies, because it changes amino acid sequence from arginine to proline. In this study a significant effect of the MYF5 and MYOG genotype on the LL muscle microstructure was not identified.