Linkage map positions of the four allergen gene families in Prunus (T × E) reference map and alignment with those in apple ( Malus domestica ) reference map. Relevant linkage map information was derived from Prunus T × E updated maps (Arús et al.) and apple (Maliepaard et al., TAG, 1998, 97:60–73; Gao et al 2005, TAG 110:479–491; 111:174–183 and 1087–1097). An initial reference for alignment is based on Dirlewanger et al. (PNAS, 2004, 101:9891–9896). A bar indicates map position range of a bin. Homologous allergen genes and common RFLP probes are underlined to show their synteny.