Illumina Sequencing of Ragweed Pollen

Common ragweed (Ambrosia artemisiifolia L.) is a highly allergenic annual ruderal plant and native to Northern America, but now also spreading across Europe. Air pollutions and climate change will not only affect plant growth, pollen production and duration of the whole pollen season, but also the amount of allergenic encoding transcripts and proteins of the pollen. The objective of this study was to get a better understanding of transcriptional changes in ragweed pollen upon NO2 and O3 fumigation. This will also contribute to a systems biology approach to understand the reaction of the allergenic pollen to air pollutions and climate change. Ragweed plants were grown in climate chambers under controlled conditions and fumigated with 40 ppb NO2 (control) and 80 ppb NO2 (treatment). The experiment was repeated using clean air (control) and 80 ppb NO2 (treatment). In the other setup plants were fumigated with 40 ppb O3 (control) and 80 ppb O3 or 120 ppb O3 (treatment). Illumina sequencing and de novo assembly revealed differentially expressed transcripts, belonging to different gene ontology (GO) terms that were grouped into biological process and molecular function. Transcript levels of the known ragweed encoding allergens were clearly up-regulated under elevated NO2, whereas the amount of allergen encoding transcripts was more variable under elevated O3 conditions. Taking together, the transcriptional changes in ragweed pollen upon elevated NO2 fumigation indicates that air pollutions will alter the transcriptome of the pollen. The changed levels of allergenic encoding transcripts may have an influence on the total allergenic potential of ragweed pollen.