Gao Zhongshan, van de Weg Eric W, Matos Catarina I, Arens Paul, Bolhaar Suzanne T H P, Knulst Andre C, Li Yinghui, Hoffmann-Sommergruber Karin, Gilissen Luud J W J
Department of Horticulture/Allergy Research Center, Zhejiang University, Hangzhou 310029, PR China.
BMC Plant Biol. 2008 Nov 13;8:116. doi: 10.1186/1471-2229-8-116.
Mal d 1 is a major apple allergen causing food allergic symptoms of the oral allergy syndrome (OAS) in birch-pollen sensitised patients. The Mal d 1 gene family is known to have at least 7 intron-containing and 11 intronless members that have been mapped in clusters on three linkage groups. In this study, the allelic diversity of the seven intron-containing Mal d 1 genes was assessed among a set of apple cultivars by sequencing or indirectly through pedigree genotyping. Protein variant constitutions were subsequently compared with Skin Prick Test (SPT) responses to study the association of deduced protein variants with allergenicity in a set of 14 cultivars.
From the seven intron-containing Mal d 1 genes investigated, Mal d 1.01 and Mal d 1.02 were highly conserved, as nine out of ten cultivars coded for the same protein variant, while only one cultivar coded for a second variant. Mal d 1.04, Mal d 1.05 and Mal d 1.06 A, B and C were more variable, coding for three to six different protein variants. Comparison of Mal d 1 allelic composition between the high-allergenic cultivar Golden Delicious and the low-allergenic cultivars Santana and Priscilla, which are linked in pedigree, showed an association between the protein variants coded by the Mal d 1.04 and -1.06A genes (both located on linkage group 16) with allergenicity. This association was confirmed in 10 other cultivars. In addition, Mal d 1.06A allele dosage effects associated with the degree of allergenicity based on prick to prick testing. Conversely, no associations were observed for the protein variants coded by the Mal d 1.01 (on linkage group 13), -1.02, -1.06B, -1.06C genes (all on linkage group 16), nor by the Mal d 1.05 gene (on linkage group 6).
Protein variant compositions of Mal d 1.04 and -1.06A and, in case of Mal d 1.06A, allele doses are associated with the differences in allergenicity among fourteen apple cultivars. This information indicates the involvement of qualitative as well as quantitative factors in allergenicity and warrants further research in the relative importance of quantitative and qualitative aspects of Mal d 1 gene expression on allergenicity. Results from this study have implications for medical diagnostics, immunotherapy, clinical research and breeding schemes for new hypo-allergenic cultivars.
Mal d 1是一种主要的苹果过敏原，可导致桦树花粉致敏患者出现口腔过敏综合征（OAS）的食物过敏症状。已知Mal d 1基因家族至少有7个含内含子的成员和11个无内含子的成员，它们在三个连锁群上成簇定位。在本研究中，通过测序或间接通过系谱基因分型评估了一组苹果品种中7个含内含子的Mal d 1基因的等位基因多样性。随后比较了蛋白质变体组成与皮肤点刺试验（SPT）反应，以研究在一组14个品种中推导的蛋白质变体与致敏性的关联。
在所研究的7个含内含子的Mal d 1基因中，Mal d 1.01和Mal d 1.02高度保守，因为十分之九的品种编码相同的蛋白质变体，而只有一个品种编码第二种变体。Mal d 1.04、Mal d 1.05和Mal d 1.06 A、B和C变异性更大，编码三到六种不同的蛋白质变体。对高致敏品种金冠与系谱相关的低致敏品种桑塔纳和普莉西拉之间的Mal d 1等位基因组成进行比较，结果表明Mal d 1.04和-1.06A基因（均位于连锁群16上）编码的蛋白质变体与致敏性之间存在关联。这一关联在其他10个品种中得到了证实。此外，基于点点试验，Mal d 1.06A等位基因剂量效应与致敏程度相关。相反，未观察到Mal d 1.01（位于连锁群13上）、-1.02、-1.06B、-1.06C基因（均位于连锁群16上）或Mal d 1.05基因（位于连锁群6上）编码的蛋白质变体之间存在关联。
Mal d 1.04和-1.06A的蛋白质变体组成，以及就Mal d 1.06A而言的等位基因剂量，与14个苹果品种之间的致敏性差异相关。这一信息表明定性和定量因素均参与了致敏性，值得进一步研究Mal d 1基因表达的定量和定性方面对致敏性的相对重要性。本研究结果对医学诊断、免疫治疗、临床研究以及新的低致敏品种的育种方案具有重要意义。
