title: A qRT-PCR assay for the expression of all Mal d 1 isoallergen genes.
abstract: BACKGROUND
  A considerable number of individuals suffer from oral allergy syndrome (OAS) to apple, resulting in the avoidance of apple consumption. Apple cultivars differ greatly in their allergenic properties, but knowledge of the causes for such differences is incomplete. Mal d 1 is considered the major apple allergen. For Mal d 1, a wide range of isoallergens and variants exist, and they are encoded by a large gene family. To identify the specific proteins/genes that are potentially involved in the allergy, we developed a PCR assay to monitor the expression of each individual Mal d 1 gene. Gene-specific primer pairs were designed for the exploitation of sequence differences among Mal d 1 genes. The specificity of these primers was validated using both in silico and in vitro techniques. Subsequently, this assay was applied to the peel and flesh of fruits from the two cultivars 'Florina' and 'Gala'.
  
  
  RESULTS
  We successfully developed gene-specific primer pairs for each of the 31 Mal d 1 genes and incorporated them into a qRT-PCR assay. The results from the application of the assay showed that 11 genes were not expressed in fruit. In addition, differential expression was observed among the Mal d 1 genes that were expressed in the fruit. Moreover, the expression levels were tissue and cultivar dependent.
  
  
  CONCLUSIONS
  The assay developed in this study facilitated the first characterisation of the expression levels of all known Mal d 1 genes in a gene-specific manner. Using this assay on different fruit tissues and cultivars, we obtained knowledge concerning gene relevance in allergenicity. This study provides new perspectives for research on both plant breeding and immunotherapy.
authors.affiliation: Wageningen UR Plant Breeding, Plant Research International, Droevendaalsesteeg 1, Wageningen, PB, 6708, The Netherlands. giulia.pagliarani2@unibo.it
authors.forename: Giulia
authors.initials: G
authors.lastname: Pagliarani
authors.forename: Roberta
authors.initials: R
authors.lastname: Paris
authors.forename: Paul
authors.initials: P
authors.lastname: Arens
authors.forename: Stefano
authors.initials: S
authors.lastname: Tartarini
authors.forename: Giampaolo
authors.initials: G
authors.lastname: Ricci
authors.forename: Marinus M J
authors.initials: MM
authors.lastname: Smulders
authors.forename: W Eric
authors.initials: WE
authors.lastname: van de Weg
mesh_terms: D000485:Allergens / Q000235:genetics* / Q000276:immunology*; D052179:Antigens, Plant / Q000235:genetics* / Q000276:immunology; D027845:Malus / Q000235:genetics* / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics* / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000485:Allergens; D052179:Antigens, Plant; D010940:Plant Proteins