Rendena cattle mitogenomes: 86 maternal haplotypes in 137 animals, T3 haplogroup phylogeny refined

Researchers sequenced complete mitochondrial genomes from 137 Rendena cattle and 31 Alpine Grey cattle, according to a study in Genetics Selection Evolution. Rendena is a dual-purpose breed from Val Rendena, an isolated Alpine valley in northern Italy. The Rendena animals were selected to represent the majority of maternal lineages across the breed. biomedcentral.comGenetics Selection Evolutionbiomedcentral.comOpen source ↗

Local breeders preserved the breed despite severe epidemics. Earlier genome-wide studies identified signatures of selection in Rendena cattle, but little was known about its evolutionary history, which the mitogenome analysis was designed to address.

Haplotype diversity and haplogroups

The authors identified 86 distinct mitochondrial DNA haplotypes in Rendena cattle, with a haplotype diversity of 0.986. Of these, 62 occurred in single animals and 24 were shared by two or more. The 31 Alpine Grey mitogenomes gave 27 haplotypes and a haplotype diversity of 0.989.

Virtually all samples belong to the T macro-haplogroup: T3 accounts for 91%, T2 for 7% and T5 for 1%. biomedcentral.comGenetics Selection Evolutionbiomedcentral.comOpen source ↗ Only one sample falls within the Q1 lineage. The Alpine Grey set showed a similar distribution, which points to strong genetic proximity of the two populations. The authors suggest either a recent common ancestry or historical maternal gene flow.

Balkan link and structure of T3

The presence of rare haplogroups T5 and Q1 together with high overall mtDNA diversity suggests a complex history of the Rendena breed, according to the authors. Analysis of Rendena variation in a West-Eurasian context revealed an ancestral link with the Balkans. No haplotype sharing was observed, which supports the uniqueness of the Rendena maternal gene pool.

The high frequency of T3 mitogenomes allowed the team to re-assess and refine the global phylogeny of this haplogroup. The refined tree shows population structuring within the Rendena breed. The authors conclude that T3, the dominant European haplogroup, is far more structured than previously recognized, reflecting post-domestication dispersal and regional differentiation.

Both Rendena and Alpine Grey cattle, in the authors' assessment, harbor high maternal diversity and preserve rare, ancient taurine lineages. They note the value of local, endangered breeds as reservoirs of unique genetic variation. biomedcentral.comGenetics Selection Evolutionbiomedcentral.comOpen source ↗