MURALIDHAR, M(MAJOR)VINOO, RKALYANA CHAKRAVARTHY, MDIANA, M2023-04-292023-04-292022-09https://krishikosh.egranth.ac.in/handle/1/5810196922THESISThe sheep genetic resources of Andhra Pradesh shows a very clear distinct coat colour pattern. Coat colour is an important economic trait in domestic sheep which vary greatly due to hereditary and environmental factors. The coat colour phenotype is influenced by a large number of genes involved in various stages of melanogenesis, from the migration and maturation of the melanocytes to the production of melanin. The agouti signaling pathway (ASIP) gene is a crucial gene that plays an important role in coat colour determination in sheep through epistatic interaction with other genes. The present study was conducted to provide insight into role of certain ASIP loci in coat colour patterns in the sheep genetic groups of Andhra Pradesh. Blood samples were collected from six sheep genetic groups of Andhra Pradesh. Modified high salt method was used for the isolation of Genomic DNA. An allele specific PCR assay was designed to study variation in the deletion locus D5 located on exon 2 of the gene. PCR-RFLP assay with PstI restriction enzyme was used to determine the non-synonymous SNP (c.5172T>A) polymorphism. Departures from Hardy-Weinberg equilibrium in each population were analyzed using a chi-square test for both the loci. As the pattern of genotypes are not consistent with the genetic groups, it is difficult to draw a conclusion with respect to D5 allele and its role in coat colour in sheep genetic groups of Andhra Pradesh. In 5172T>A SNP, it is interesting to note that how a black coat colour influencing allele under homozygous condition is producing white coat colour in Nellore Palla. No single genetic group is associated with specific genotype for either of the loci so, a total of nine possible combination of diplotypes were scored. However, no specific diplotype is associated with the genetic group. From this, it is plausibly deduced that the combination of wild type at the deletion locus and T allele at the non-synonymous locus could plausibly be giving rise to the white coat colour in these genetic groups except in Nellore Brown which may be due to interactions with other coat colour loci. In order to get better understanding about genetics of coat colour in the native sheep genetic groups of Andhra Pradesh, studies involving coat colour loci other than ASIP gene and specific coat colour pattern of each individual is necessary.EnglishThesis