Validation of a functional molecular marker suitable for marker-assisted breeding for fruit texture in apple (Malus x domestica Borkh.)

Molecular markers are nowadays considered fundamental tools in breeding programs, supporting the selection of the most favourable offspring. This role is invaluable in the case of complex agronomic traits in tree fruit crop species, such as fruit texture in apple (Malus x domestica Borkh.). This work presents the validation of a previously identified functional simple sequence repeat marker, named Md-PG1(SSR)10kd, suitable for the advanced selection of high texture performance seedlings. Two independent populations were chosen by marker-assisted parent selection, and a specific set of seedlings was selected by marker-assisted seedling selection, to validate the predictive power of this marker. The two groups of seedlings, further phenotyped for fruit texture, showed a clear difference in texture behaviour. The selection of this marker also showed a higher efficiency than Md-ACS1 and Md-ACO1, two functional markers currently implemented in different breeding programs. Finally, the allelic effect was estimated by computing the breeding values in a collection of 83 different apple cultivars. The results reported here confirmed the association of Md-PG1(SSR)10kd with texture sub-traits, proposing this as a novel promising selection strategy suitable for apple fruit texture.