Expression Of MLPH?PMEL17 Genes And Correlation Analysis Between Snps And Melanin Deposition In Xuefeng Black-Boned Chicken

Xuefeng black-boned chicken is the only kind of meat-and-egg-type black-boned chickens in Hunan,Meanwhile,which is precious in China.Xuefeng black-boned chicken's meat quality is fresh and tender,nutrient rich,and has health functions.The medicinal value of black-bone chicken is related to melanin.Compendium of Materia Medica records that "the color is darker and the efficacy is better";Which leads the consumers are more likely to have darker black chicken.However,there are big differences among Xuefeng black-boned chicken individuals for melanin deposition.And the conventional breeding has a long period.The melanin deposition in muscle could only be selected by other reference index like skin color and shank color,while the accuracy is low.The white line of Xuefeng black-boned chicken was used as test material,in this study,to research molecular assisted breeding techniques about melanin in Xuefeng black-boned chicken white line.Therefore,the difference in melanin content,and the black degree of the breast muscle were analyzed,the relationship between black degree and melanin content was established.The gene expression difference and mutation of MLPH and PMEL17 genes were detected.The main results are as follows:1.The color and melanin content of breast muscle in Xuefeng black-boned chicken Analysis of melanin content showed that the average melanin content in the breast muscle tissue of black-boned chicken with a high black degree was 0.417±0.028 mg/g,while it was 0.175±0.009 mg/g for those with a low black degree.The melanin content of the former was significantly higher(P<0.05)than the latter's.W value was extremely significantly positively(P<0.01)correlated with the melanin content,which could be used as a reference index of melanin content,and the regression model is:y=0.3079x-0.3815,R2=0.7078.2.Comparison of gene expression levels of MLPH and PMEL17 in breast muscle with different black degrees.The expression of MLPH gene in breast muscle tissue with a high black degree was significantly higher(P<0.05)than those with a low black degree.The expression ofPMEL17 gene in breast muscle tissue with a high black degree was extremely significantly higher(P<0.01)than those with a low black degree,There was extremely significantly positively correlated(P<0.01)between MLPH,PMEL17 genes expression and melanin content of Xuefeng black-boned chicken breast muscle,indicating that the higher gene expression is more beneficial to the melanin deposition.3.SNPs screening of MLPH and PMEL17 geneSNPs(single nucleotide polymorphisms)screened the two candidate genes by direct sequencing,it showed that a total of 17 mutations were found in the MLPH gene,and a total of 11 mutations were found in the PMEL17 gene.The correlation analysis of SNPs site and melanin content of breast muscle showed that the C-1411 T site on intron 1 of the MLPH gene,and the G-1843 C site on intron 2,C-2812 T and G-2794 A site on exon 6 of the PMEL17 gene were significantly associated with melanin deposition in the breast muscle.In conclusion,the above results indicate that MLPH and PMEL17 genes are associated with melanin deposition in the breast muscle of Xuefeng black-boned chicken,Moreover,significantly associated SNPs sites are found,which can be used as molecular markers for the melanin deposition in breast muscle.This study provides a theoretical basis for the breeding of Xuefeng black-boned chicken,and has enriched the information on breed protection and selection for local varieties.