Ragweed (Ambrosia artemisiifolia) pollen allergenicity: SuperSAGE transcriptomic analysis upon elevated CO2 and drought stress

Abstract

BackgroundPollen of common ragweed (Ambrosia artemisiifolia) is a main cause of allergic diseases in Northern America. The weed has recently become spreading as a neophyte in Europe, while climate change may also affect the growth of the plant and additionally may also influence pollen allergenicity. To gain better insight in the molecular mechanisms in the development of ragweed pollen and its allergenic proteins under global change scenarios, we generated SuperSAGE libraries to identify differentially expressed transcripts.ResultsRagweed plants were grown in a greenhouse under 380 ppm CO2 and under elevated level of CO2 (700 ppm). In addition, drought experiments under both CO2 concentrations were performed. The pollen viability was not altered under elevated CO2, whereas drought stress decreased its viability. Increased levels of individual flavonoid metabolites were found under elevated CO2 and/or drought. Total RNA was isolated from ragweed pollen, exposed to the four mentioned scenarios and four SuperSAGE libraries were constructed. The library dataset included 236,942 unique sequences, showing overlapping as well as clear differently expressed sequence tags (ESTs). The analysis targeted ESTs known in Ambrosia, as well as in pollen of other plants. Among the identified ESTs, those encoding allergenic ragweed proteins (Amb a) increased under elevated CO2 and drought stress. In addition, ESTs encoding allergenic proteins in other plants were also identified.ConclusionsThe analysis of changes in the transcriptome of ragweed pollen upon CO2 and drought stress using SuperSAGE indicates that under global change scenarios the pollen transcriptome was altered, and impacts the allergenic potential of ragweed pollen.

The Health Effects of Climate Change in the WHO European Region

“…A recent study of Timothy grass (Phleum pratense), commonly found across Europe and a frequent cause of seasonal allergies, found that exposure to elevated concentrations of carbon dioxide increased the amount of pollen produced by each flower by approximately 50% [195]. Furthermore, studies of Ragweed (Ambrosia artemisiifolia) suggest that both recent and projected increases in atmospheric carbon dioxide concentration may increase the amount of allergenic pollen produced [196,197]. …”

Effects of NO<sub>2</sub> on Inflorescence Length, Pollen/Seed Amount and Phenolic Metabolites of Common Ragweed (<i>Ambrosia artemisiifolia</i> L.)

“…Changes in individual phenolic metabolites have also been reported in A. artemisiifolia pollen upon CO 2 and/or drought stress [43], whereas no changes were observed upon ozone fumigation [14]. The pollen of several other plants species that were sampled from polluted and less-polluted areas showed an increased amount of individual flavonoids [44] [45].…”

Ragweed Pollen Allergy: Burden, Characteristics, and Management of an Imported Allergen Source in Europe

“…The expression of Amb a 1.01, 1.02, and 1.03 isoallergens could be upregulated under certain environmental situations, such as elevated CO 2 or drought stress, which has been shown in greenhouse experiments [38]. Also, environmental factors such as temperature, humidity, and light had a significant influence on Amb a 1 content [32].…”

“…Such enzymes are important for pollen growth by degrading pectines [38]. More than 90% of ragweed-allergic patients are sensitized to this major allergen [39].…”