A genomic map of climate adaptation in Mediterranean cattle breeds.

Domestic species such as cattle (Bos taurus taurus and B. t. indicus) represent attractive biological models to characterize the genetic basis of short-term evolutionary response to climate pressure induced by their post-domestication history. Here, using newly generated dense SNP genotyping data, we assessed the structuring of genetic diversity of 21 autochtonous cattle breeds from the whole Mediterranean basin and performed genome-wide association analyses with covariables discriminating the different Mediterranean climate subtypes. This provided insights into both the demographic and adaptive histories of Mediterranean cattle. In particular, a detailed functional annotation of genes surrounding variants associated with climate variations highlighted several biological functions involved in Mediterranean climate adaptation such as thermotolerance, UV protection, pathogen resistance or metabolism with strong candidate genes identified (e.g., NDUFB3, FBN1, METTL3, LEF1, ANTXR2 and TCF7). Accordingly, our results suggest that main selective pressures affecting cattle in Mediterranean area may have been related to variation in heat and UV exposure, in food resources availability and in exposure to pathogens, such as anthrax bacteria (Bacillus anthracis). Furthermore, the observed contribution of the three main bovine ancestries (indicine, European and African taurine) in these different populations suggested that adaptation to local climate conditions may have either relied on standing genomic variation of taurine origin, or adaptive introgression from indicine origin, depending on the local breed origins. Taken together, our results highlight the genetic uniqueness of local Mediterranean cattle breeds and strongly support conservation of these populations.

Allele and genotype frequencies of ß-lactoglobulin gene using PCR-RFLP in Algerian local cattle populations.

Milk protein genetic polymorphisms are associated with economically important traits in dairy cattle. The objective of this study is to genotype a single nucleotide polymorphism (SNP) responsible for the amino acid changes in the beta-lactoglobulin (ß-Lg) variants A and B on 85 unrelated DNA representing Algerian cattle populations: Chelifienne (28), Cheurfa (31) and Guelmoise (26). The method used is the PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism). Genetic polymorphism was detected by digestion of PCR products amplified of exon II of ß-Lg gene by with the endonuclease HaeIII enzyme. The results revealed that the amplified product was observed as 247 bp. Restriction digestion with HaeIII revealed three genotypes: AA, AB and BB. The genotypic frequencies of AA, AB and BB genotypes were 0.08, 0.41, 0.50; 0.08, 0.41, 0.50 and 0.01, 0.19, 0.56 in Chelifienne, Cheurfa and Guelmoise and respectively. Frequency of AA genotype was absent in Guelmoise population. Frequencies of A and B alleles were 0.29 and 0.71 in both Chelifienne and Cheurfa and 0.25 and 0.75 Guelmoise population. These results further confirm that Bos torus cattle are predominantly of ß-Lactoglobulin B type. The Chi-square test at p-value < 0.05 results revealed that the Chelifienne and Cheurfa populations were in Hardy-Weinberg equilibrium and the results are not significant for the Guelmoise. This genetic information could be useful to estimate the effect of polymorphism on different milk production of Algerian bovine populations.