A Model System to Study the Environment-Dependent Expression of the <i>Bet v 1a</i> Gene Encoding the Major Birch Pollen Allergen

Abstract

Background: The major birch pollen allergen Bet v 1 (or Bet v 1a) is one of the main causes of seasonal type I allergies. Various environmental factors such as light, temperature and air pollution may influence the activity of the Bet v 1a gene. The creation of a model system to evaluate the role of environmental factors affecting the Bet v 1a gene expression would be highly desirable. We suggest the use of transgenic tobacco plants carrying a Bet v 1a promoter-reporter gene fusion as such a system. Methods: The promoter of the Bet v 1a gene was isolated with the use of the Universal Genome Walker kit (BD Biosciences Clontech, USA). Web Software was used to search for putative cis-regulatory elements within the promoter. Transgenic tobacco plants harboring the promoter-β-glucuronidase (GUS) reporter gene fusion were obtained via Agrobacterium tumefaciens-mediated transformation. Promoter activity was examined with histochemical and quantitative assays. Results: Structural analysis predicted elements responsible for pollen-specific, light-, stress- and hormone-mediated induction within the Bet v 1a promoter. The evaluation of GUS activity in transgenic tobacco plants showed that the Bet v 1a promoter is pollen-specific. Moreover, the Bet v 1a promoter is considered to be the strongest isolated pollen-specific promoter reported to date. It was shown that temperature and abscisic acid positively regulate the activity of the Bet v 1a promoter during pollen development, providing evidence for environment-dependent regulation of the Bet v 1a gene. Conclusions: A model system to study the effect of environmental factors on the expression of the Bet v 1a gene encoding the major birch allergen in pollen was generated. Additionally, we suggest that this system could be used to search for factors that inhibit the activity of the gene in pollen in order to reduce the potential allergenicity of birch trees.

High Environmental Ozone Levels Lead to Enhanced Allergenicity of Birch Pollen

“…While Ahlholm et al [22] reported a positive effect of high temperatures on Bet v 1 content, Helander et al [23] indicated a negative association. The effect of temperature on the expression of Bet v 1 was also investigated by Tashpulatov et al [24] , using transgenic tobacco plants carrying a Bet v 1a-pomoter-reporter gene fusion. This study showed that warm temperatures positively regulate the activity of the Bet v 1 promoter.…”

Year-to-Year Variation in Release of Bet v 1 Allergen from Birch Pollen: Evidence for Geographical Differences between West and South Germany

“…The release of Bet v 1 from pollen is known to depend on the climatic conditions and side of the tree sampled [28, 35, 36]. The composition of the soil, the stage of the natural cycle the tree is in [37, 38], and the health status and genus of a tree are all likely to be important factors [39], as is well known for many commercially used plants [40].…”

Effect of nitrogen dioxide and sulfur dioxide on viability and morphology of oak pollen

“…Several studies have indicated that air pollutants can also interact with and modify the allergen carrier itself; ie, the plant and its pollen grains. There is a large body of evidence that air pollutants influence gene expression and can provoke modifications in the membrane structures, interfering with the cellular mechanisms . In this regard, NO 2 present in the urban air has been shown to interact with pollen grains, inducing modifications in fertility and protein content that affect the reproductive cycle of spermatophytes .…”