‘Brünnerling’ group show that close relatedness and polyploidy make apple genetic diversity highly complex

This study uses molecular marker data from the apple cultivar collection of the German Fruit Genebank (GFG) to test the genetic coherence of the literature-defined ‘Brünnerling’ group and to resolve mislabelling and relationships through kinship/parentage and genetic distance analyses. Parentage and genetic distance-based analyses showed that ‘Brünnerling’ cultivars can be distinguished on the molecular level. ‘Kleiner Brünnerling’ (Malus UNiQue genotype code (MUNQ) 2284) was identified as a major progenitor within the cultivar group. Pedigree relationships among the ‘Brünnerling’ cultivars are complex, particularly for triploid cultivars. Parentages from previous studies were confirmed with regard to MUNQs. For the putative triploid cultivar ‘Bühlers Erdbeerapfel’ (MUNQ 898), the genetic fingerprint data corresponded to the transfer of an unreduced gamete from MUNQ 8143, which is one of the two parental genotypes. In addition, it was also possible to identify the second parent. In the distance-based tree, the ‘Brünnerling’ cultivars formed a cluster with other cultivars, and the central role of ‘Kleiner Brünnerling’ was further highlighted.