| The resources of pig breeds in China are very plentiful,and the existing indigenous pig breeds account for about one third of the world’s pig genetic resources.At the same time,China’s local pig production needs to strengthen the research and development of pig breeding from a biological science perspective in order to optimise the meat quality traits of local pigs,which shows that pig breeding is one of the irreplaceable pillar industries in China’s livestock industry.Pig meat quality is a complex and comprehensive trait that can be evaluated by a number of different indicators,such as meat color,p H,water retention,marbling,intramuscular fat content,tenderness and flavour.Of these indicators,meat color is one of the most important factors influencing consumers’ purchasing decisions,as they cannot evaluate the taste or feel the quality of the meat without opening the package.With hundreds of millions of dollars in economic losses due to abnormal meat color in recent years,it is clear that meat color improvement has become a worldwide problem that needs to be tackled,mainly because currently meat color phenotypes are determined by visual observation of colourimetric or optical measurements,which are not specific enough and limit the genetic improvement of meat color traits.Myoglobin(Mb)is the material basis for the color of pork,and different degrees of meat color depend on the level of Mb.However,the lack of genomic information has limited the understanding of the mechanism of Mb regulation in pigs,and the genetic analysis of meat color has not been sufficiently studied in terms of Mb content as a phenotype.In this experiment,we first identified for the promoter sequence of the Mb gene from the primary assembly of the pig high-throughput genome sequencing and predicted its potential 98 transcription factors by LASAGNA.By data mining the m RNA expression profiles of the longest dorsal muscle of different pig breeds,we constructed an interaction network of Mb-TFs consisting of 16 adaptive core transcription factors and 23 secondary transcription factors.We used small Bama pigs and large Yorkshire pigs as experimental animals and showed by in vitro validation that the Mb gene was significantly higher in Bama pigs than in Yorkshire pigs at both m RNA and protein expression levels.The q RT-PCR validation of the Mb-TFs interaction network showed that FOS,STAT3,STAT1,NEFL21,NFE2L2 and MAFB were the core positive regulatory transcription factors in the Mb-TFs interaction network(P<0.0001),and the expression of these transcription factors was significantly higher in the longissimus dorsi muscle of Bama pigs than in Yorkshire pigs.The relationship between mi RNAs and meat quality depends on factors such as muscle fibre composition and intramuscular fat content,which determine meat color,flavour,juiciness and water retention.To further explore more mechanisms that may regulate Mb gene-related mi RNAs and their possible roles and effects on meat quality,we used the BLAST localization program to compare eight mi RNAs: mi R-128,mi R-9798-3p,mi R-671-3p,mi R-9805-3p,mi R-9792-5p,mi R-423-5p and mi R-708-5p.mi R-423-5p,mi R-128,mi R-9805-3p and mi R-708-5p were significantly more expressed in LD tissues than in Yorkshire pigs by q RT-PCR.mi R-9791-3p,mi R-9798-3p and mi R-671-3p were significantly more expressed in LD tissues than in Yorkshire pigs(P<0.0001).mi R-9791-3p,mi R-9798-3p and mi R-671-3p were significantly more expressed in LD tissues than in Yorkshire pigs.mi R-9791-3p,mi R-9798-3p and mi R-671-3p were all significantly more expressed in LD tissues from Yorkshire pigs than from Balsam pigs(P<0.0001);mi R-9792-5p was not significantly different in LD tissues from both pigs.Meanwhile,the basal expression of these eight mi RNAs ranged under 0.15,all of which were low efficiency mi RNA,inferring that the posttranscriptional negative regulatory effect of Mb genes from mi RNA was small.Combining the above experimental results,we inferred that these transcription factors and mi RNA may be factors affecting the Mb gene,the main gene of pork color.Our study provides a new strategy to unravel the mechanism of pork color formation and lay the foundation for improving meat quality traits. |
