I.M. van der Meer

Genomic cloning and linkage mapping of the Mal d 1 (PR-10) gene family in apple (Malus domestica).

Fresh apples can cause birch pollen-related food allergy in northern and central European populations, primarily because of the presence of Mal d 1, the major apple allergen that is cross-reactive to the homologous and sensitizing allergen Bet v 1 from birch. Apple cultivars differ significantly in their allergenicity. Knowledge of the genetic basis of these differences would direct breeding for hypoallergenic cultivars. The PCR genomic cloning and sequencing were performed on two cultivars, Prima and Fiesta, which resulted in 37 different Mal d 1 gDNA sequences. Based on the mapping of sequence-specific molecular markers, these sequences appeared to represent 18 Mal d 1 genes. Sixteen genes were located in two clusters, one cluster with seven genes on linkage group (LG) 13, and the other cluster with nine genes on the homoeologous LG 16. One gene was mapped on LG 6, and one remained unmapped. According to sequence identity, these 18 genes could be subdivided into four subfamilies. Subfamilies I–III had an intron of different size that was subfamily and gene-specific. Subfamily IV consisted of 11 intronless genes. The deduced amino acid sequence identity varied from 65% to 81% among subfamilies, from 82% to 100% among genes within a subfamily, and from 97.5% to 100% among alleles of one gene. This study provides a better understanding of the genetics of Mal d 1 and the basis for further research on the occurrence of allelic diversity among cultivars in relation to allergenicity and their biological functions.

Linkage map positions and allelic diversity of two Mal d 3 (non-specific lipid transfer protein) genes in the cultivated apple (Malus domestica).

Non-specific lipid transfer proteins (nsLTPs) of Rosaceae fruits, such as peach, apricot, cherry, plum and apple, represent major allergens for Mediterranean atopic populations. As a first step in elucidating the genetics of nsLTPs, we directed the research reported here towards identifying the number and location of nsLTP (Malxa0dxa03) genes in the apple genome and determining their allelic diversity. PCR cloning was initially performed on two cultivars, Prima and Fiesta, parents of a core apple mapping progeny in Europe, based on two Malxa0dxa03 sequences (AF221502 and AJ277164) in the GenBank. This resulted in the identification of two distinct sequences (representing two genes) encoding the mature nsLTP proteins. One is identical to accession AF221502 and has been named Malxa0dxa03.01, and the other is new and has been named Malxa0dxa03.02. Subsequent genome walking in the upstream direction and DNA polymorphism analysis revealed that these two genes are intronless and that they could be mapped on two homoeologous segments of linkage groupsxa012 and 4, respectively. Further cloning and sequencing of the coding and upstream region of both Malxa0dxa03 genes in eight cultivars was performed to identify allelic variation. Assessment of the deduced nsLTP amino acid sequences gave a total of two variants at the protein level for Malxa0dxa03.01 and three for Malxa0dxa03.02. The consequences of our results for allergen nomenclature and the breeding of low allergenic apple cultivars are discussed.

Why Oats Are Safe and Healthy for Celiac Disease Patients

The water-insoluble storage proteins of cereals (prolamins) are called “gluten” in wheat, barley, and rye, and “avenins” in oat. Gluten can provoke celiac disease (CD) in genetically susceptible individuals (those with human leukocyte antigen (HLA)-DQ2 or HLA-DQ8 serotypes). Avenins are present at a lower concentration (10%–15% of total protein content) in oat as compared to gluten in wheat (80%–85%). The avenins in the genus Avena (cultivated oat as well as various wild species of which gene bank accessions were analyzed) are free of the known CD immunogenic epitopes from wheat, barley, and rye. T cells that recognize avenin-specific epitopes have been found very rarely in CD patients. CD patients that consume oats daily do not show significantly increased levels of intraepithelial lymphocyte (EIL) cells. The safety and the positive health effects of the long-term inclusion of oats in the gluten-free diet have been confirmed in long-term studies. Since 2009 (EC 41/2009) and 2013 (FDA) oat products may be sold as gluten-free in several countries provided a gluten contamination level below 20 ppm. Introduction of oats in the gluten-free diet of celiac patients is advised after the recovery of the intestine. Health effects of oat consumption are reflected in European Food Safety Authority (EFSA)- and Food and Drug Administration (FDA)-approved health claims. Oats can form a healthy, nutritious, fiber-rich, and safe complement to the gluten-free diet.

Towards prevention of allergy through an integrated multidisciplinary approach

Abstract Both food- and environmentally-related allergies are a continually growing health problem, particularly in the western world. The exact causes and the additional environmental and social factors that play a role in the onset of these illnesses are still poorly understood. While sufferers of allergy remain a minority in society, the reduction of their quality of life and the financial consequences for society as a whole are of major significance. Allergy is an illness that confronts the sufferer on a daily basis with his or her life style limitations. The direct and indirect annual costs to society (medical care, sick leave, loss of earnings, reduced productivity] are already running well into billions of euros. A complicating factor is that there are many kinds of allergy, with many different causes, requiring several approaches for treatment. There is no single solution. Much social and scientific research is still needed to generate additional knowledge required to determine a suitable multidisciplinary strategy for the long-term tackling of this problem. Input from a wide range of sources, including social scientists, medics, agronomists and immunologists, is essential to fully assess the situation and to assist in determining long-term policy decisions at a national level. This multidisciplinarity calls for broad support from different sections of government, industry and societal bodies to achieve the desired goal of reversing the rise in the number of allergy sufferers, preferably through prevention rather than cure. In this article we present the most salient items from the presentations and discussions of a workshop on the agronomic approaches to allergy prevention, recently held in the Netherlands.

Acceptance of Natural and Genetically Modified Hypoallergenic Apples by Consumers with an Oral Allergy Syndrome (OAS)

Plant Research International, together with UMC-Utrecht, screened a wide collection of existing apple varieties for allergenicity, and identified the Santana as a hypoallergenic variety. This variety was introduced on the market in 2006 as “suitable for consumption by consumers with a mild apple allergy”. Its packaging included a background information leaflet, a protocol regarding how to eat it (in relation to “testing” for allergic reactions) and a link to a consumer questionnaire. The results of this questionnaire showed that a high percentage of consumers had no, or very slight, complaints after eating this hypoallergenic cultivar Santana. The questionnaire also included some questions on the appreciation of hypoallergenic apple varieties if they were to be produced by genetic modification. This chapter elaborates on the acceptance by Dutch consumers of hypoallergenic apples, developed either by breeding or by genetic modification.