Phenotypic and genetic characterization of “Aglione della Valdichiana”: Population structure and genetic relationship analysis of a white gentle giant

•“Aglione della Valdichiana” was compared to leek and garlic in two field trials and by AFLPs.•Aglione della Valdichiana is genetically closer to garlic than to leek.•Despite its sterility, the within accession genetic variability of Aglione is higher than expected.•Leek parted in two separated sub-groups: with advanced cultivars and with wild accessions.