The inherent allergens of citrus fruits, such as Cit s 1, Cit s 2, Cit s 3 can cause allergic reactions. A better understanding of the genetic factors (cultivar to cultivar) affecting the allergenic potential of citrus fruits would be beneficial for further identification of hypoallergenic genotypes. In the present study, an immunoblotting quantification approach was adopted to assess the potential allergenicity of 21 citrus cultivars, including nine subgroups (tangerine, satsuma, orange, pummelo, grapefruit, lemon, kumquat, tangor, and tangelo). To prepare highly sensitive and specific rabbit polyclonal antibodies, antigenicity of purified rCit s 1.01, rCit s 2.01, and rCit s 3.01 peptides were enhanced with high epitope density in a single protein molecule. The data integration of three citrus allergen quantifications demonstrated that the four pummelo cultivars (Kao Phuang Pummelo, Wanbai Pummelo, Shatian Pummelo, and Guanxi Pummelo) were potential hypoallergenic, compared with other 8 subgroups. Moreover, the immunological analyses with sera of allergic subjects revealed that Shatian Pummelo and Guanxi Pummelo showed the lowest immunoreactivity in 8 representative citrus cultivars. These potential hypoallergenic genotypes are of great significance to not only allergic consumers but also citrus breeders in the genetic improvement of hypoallergenic citrus as breeding resources.
Keywords: citrus allergen; genetic factors; hypoallergenic fruit; immunoblotting; recombinant antigen.