Identification of allergenomic signatures in allergic and well-tolerated apple genotypes using LC-MS/MS

The apple fruit (Malus domestica L. Borkh) is one of the most popular fruits worldwide. Beyond their beneficial properties, apples contain proteins that trigger allergic reactions in susceptible consumers. Mal d1 to d4 are allergens present in a variety of different isoforms in apples. In this study, we used proteomics to quantify all four Mal d proteins in 52 apple genotypes with varying allergenic potentials. A total of 195, 17, 14, and 18 peptides were found to be related to Mal d1, d2, d3, and d4 proteins, respectively of which 25 different Mal d proteins could be unambiguously identified. The allergenic potential of the Mal d isoforms was characterized by comparing the isoform abundance with the allergenic score of genotypes from oral challenge tests. The detected Mal d peptides presumably have different IgE binding properties and could be used as potential molecular markers to discriminate between hypoallergenic and hyperallergenic cultivars.