The Relationship Between Whole Genome DNA Methylation And Pork Color And The Effects Of Betaine On Meat Color

Pork occupies a large share in China’s meat consumption market.With the rapid development of animal husbandry industry and the improvement of people’s living standards in China,pork quality requirement is becoming more and more significant.How to improve and guarantee the quality of pork is an urgent issue to be solved in China’s pig breeding industry.The main indicators of pork quality are:meat color,pH,hydraulic power,intramuscular fat and tenderness.Among them,the meat color is the most intuitive,and it directly determines the consumer’s desire to purchase.Therefore,the improvement of meat color traits from the perspective of genetics and nutrition in pig production,and the provision of high-quality pork for the majority of producers and consumers will be beneficial to the prosperity of the pork market and to the pleasure experience of people’s taste buds,with important economic and social significance.In this study,the whole genome DNA methylation sequencing technology was used to reveal the relationship between the difference of meat color and DNA methylation levels.The effects of betaine on meat color was verified in mice,which provides a theoretical basis for nutrition regulation of meat color phenotype.1.To reveal the relationship between meat color and DNA methyl level by using whole-genome DNA methylation sequencing technologyThe same individual has the identical genetic background,but the color of skeletal muscle in different parts of the same individual is not the identical.DNA methylation is one of the major epigenetic mechanisms.Without alteration of genetic sequence,a methyl is obtained by covalent binding,which regulates gene expression to change phenotype.In order to explore whether DNA methylation is related to meat color,6 libraries were constructed based on 6 samples of Soleus muscle(red muscle)and biceps Femoris muscle(white muscle)from three half-sibling Duroc Meishan sows.These libraries were Bf28,Bf35,Bf36,So128,So135 and So136,respectively.Whole Genome Bisulfite Sequencing was used to sequence the whole genome DNA.High throughput sequencing showed that 428706065,428658340,465398552,359285104,366643747,3362194492 and 384911257 Clean Reads were obtained from six libraries.The ratio of Reads to porcine reference genome measured by 6 libraries was 84.64%,85.94%,85.52%,85.16%,85.96%and 85.42%respectively.According to the data and maps obtained by sequencing,the DNA methylation profiles of the whole genome of skeletal muscles with different meat colors in two different parts were analyzed,and the differences of DNA methylation between them were explored.The results showed that the methylation level of the whole genome of red muscle(Soleus muscle)is different from that of white muscle(Biceps femoris).The relationship between whole genome DNA methylation and pork color was preliminarily clarified.2.To verify the effect of betaine on meat colorBetaine is an important methyl group,which is absorbed by the small intestine and then participates in the methionine cycle.It provides methyl groups for most methylation reactions in the body and promotes the occurrence of methylation.Therefore,in this study,48 four-week-old healthy ICR mice(purchased from Nanjing Qinglongshan Experimental Animal Breeding Plant)were selected as experimental groups and randomly divided into 4 treatments,with basic diets,0.5%,1.0%,and 2.0%betaine basic diets respectively.The base diet of betaine was fed to mice for 28 days.The results showed that:(1)The addition of betaine had no significant effect on growth performance;(2)The addition of betaine could change the whole genome methylation level of soleus and gastrocnemius which was found by using immunohistochemical 5mC-antibody labeling;(3)The meat color of skeletal muscles was detected by chemical method,and the betaine had a significant improvement effect on the meat color.(4)The expression of the slow muscle fiber genes(MyHC-Ⅰ and TNNC1)was significantly up-regulated by RT-PCR(P<0.05 or P<0.01),while the fast muscle fiber genes(MyHC-Ⅱa,MyHC-Ⅱb,MyHC-Ⅱx,TNNC2)had no significant effects.