Apple allergens genomics and biotechnology: unravelling the determinants of apple allergenicity

Abstract In the last decades allergies are increasing in the western countries and different protein families were identified as determinants of allergenicity. In apple fruit, one of the most important fruit crop in the world, four allergen families (Mal d 1 to 4) have been identified so far, including pathogenesis-related proteins 10, thaumatin-like proteins, lipid-transfer proteins and profilins. Moreover, it has been demonstrated that patient’s sensitivity differs in relation to apple variety, fruit tissue, cultivation and conservation conditions, increasing the difficulties to associate genetic, molecular and biochemical data with the results of clinical tests. Mapping studies and the availability of the complete apple genome sequence confirmed that allergens are organized in large families with many different isoforms, which contribution to allergenicity is still largely unknown. The unravelling of allergy determinants is crucial for different reasons: i) to better understand environmental influences on allergenicity; ii) to produce genetically modified plants with a reduced allergen content through a targeted-gene silencing approach and iii) to drive future breeding programs toward hypoallergenic apple through the exploitation of natural variability. Finally, the above-mentioned knowledge will be essential to allow the consumption of this fruit by individuals who are allergic to apple.