Varietal Differences in Transcript and Protein Levels of Strawberry Allergen Fra a 1

Fruit allergies are serious health problems that limit quality of life. In patients with a fruit allergy, the symptoms are generally mild and mostly limited to the oral cavity, hence the term oral allergy syndrome. To minimize these allergies, a method for screening hypoallergenic genotypes in strawberry is essential. A major strawberry allergen is Fra a 1, an orthologous protein to the major birch pollen allergen Bet v 1. In this study, gene transcript and protein levels of Fra a 1 were compared among strawberry fruits (receptacles and achenes) of eleven different cultivars. Nine cultivars were purchased from local markets, one was harvested directly from a working farm, and one was sampled from an experimental farm. Each cultivar was screened and ranked by its relative gene expression ratio of Fra a 1 to EF1α, the internal control. Protein accumulation was analyzed by immunoblot using guinea pig polyclonal antibody raised against His-tagged recombinant Fra a 1. The cultivars ‘Tochiotome’ and ‘Akihime’ were selected for further analysis because they showed significantly different expressions of Fra a 1. Fruits of these two cultivars were gathered from different areas to examine Fra a 1 expression in response to local environments. The Fra a 1 transcript levels differed among fruits grown in different areas. However, average expression levels of the two cultivars showed the same rank order. The two cultivars were also grown under the same conditions in a glass greenhouse to compare the accumulation of Fra a 1 in their fruits, and again, the cultivars had the same rank order of both Fra a 1 transcripts and protein levels. These findings suggest that the profile of Fra a 1 gene transcription is similar to that of the protein expression and might be used as a basic estimate of allergenic differences among cultivars by removing environmental effects. This work was supported by Hyogo Alliance of Universities and Colleges for Innovation and by JSPS KAKENHI Grant Number 24658030.