• An understanding of the relationship between the cultivated apple (Malus domestica) and its primary wild progenitor species (Msieversii) not only provides an understanding of how apples have been improved in the past, but may be useful for apple improvement in the future. We measured 10 phenotypes in over 1000 unique apple accessions belonging to Mdomestica and Msieversii from Canada’s Apple Biodiversity Collection. Using principal components analysis (PCA), we determined that Mdomestica and Msieversii differ significantly in  phenotypic space and are nearly completely distinguishable as two separate groups. We found that Mdomestica had a shorter juvenile phase than Msieversii and that cultivated trees produced flowers and ripe fruit later than their wild progenitors. Cultivated apples were also 3.6 times heavier, 43% less acidic, and had 68% less phenolic content than wild apples. Using historical records, we found that apple breeding over the past 200 years has resulted in a trend towards apples that have higher soluble solids, are less bitter, and soften less during storage. Our results quantify the significant changes in phenotype that have taken place since apple domestication, and provide evidence that apple breeding has led to continued phenotypic divergence of the cultivated apple from its wild progenitor species.

    Authored by:
    Thomas Davies,Sophie Watts,Kendra McClure,Zoƫ Migicovsky,Sean Myles
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