Study of polymorphisms in the promoter region of ovine β-lactoglobulin gene and phylogenetic analysis among the Valle del Belice breed and other sheep breeds considered as ancestors

摘要

The aim of this work was to sequence theudpromoter region of b-lactoglobulin (BLG) gene in fourudsheep breeds, in order to identify polymorphisms, infer andudanalyze haplotypes, and phylogenetic relationship amongudthe Valle del Belice breed and the other three breedsudconsidered as ancestors. Sequencing analysis and alignmentudof the obtained sequences showed the presence of 36udsingle nucleotide polymorphisms (SNPs) and one deletion.udA total of 22 haplotypes found in ‘‘best’’ reconstructionudwere inferred considering the 37 polymorphic sites identified.udHaplotypes were used for the reconstruction of audphylogenetic tree using the Neighbor-Joining algorithm.udThe number of polymorphisms identified showed highudvariability within breeds. Analysis of genetic diversityudindexes showed that the Sarda breed presented the lowestudnucleotide diversity, whereas the Comisana breed presentedudthe highest one. Comparing the nucleotide diversityudamong breeds, the highest value was obtained betweenudValle del Belice and Pinzirita breeds, whereas the lowestudone was between Valle del Belice and Sarda breeds.udConsidering that polymorphisms in the promoter region ofudBLG gene could have a functional role associated with milkudcomposition, the lowest value of nucleotide diversityudbetween Valle del Belice and Sarda breeds may be related to a higher similarity of milk composition of these twoudbreeds compared to the others. Further analyses will beudconducted in order to evaluate the possible correlationudbetween the genetic diversity indexes and the BLG contentudin milk of our breeds.