Open Access Research article

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

Amr El Kelish12, Feng Zhao1, Werner Heller1, Jörg Durner13, J Barbro Winkler4, Heidrun Behrendt56, Claudia Traidl-Hoffmann69, Ralf Horres7, Matthias Pfeifer8, Ulrike Frank16* and Dieter Ernst16

Author Affiliations

1 Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany

2 Botany Department, Faculty of Science, Suez Canal University, Ismailia, Egypt

3 Biochemical Plant Pathology, Technische Universität München, Center of Life and Food Sciences Weihenstephan, 85350 Freising-Weihenstephan, Germany

4 Research Unit for Environmental Simulation, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany

5 Center of Allergy & Environment München (ZAUM), Technische Universität and Helmholtz Zentrum München, 85764 Neuherberg, Germany

6 CK-CARE, Christine Kühne – Center for Allergy Research and Education, Davos, Switzerland

7 GenXPro GmbH, 60438 Frankfurt am Main, Germany

8 Institute of Bioinformatics and Systems Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Neuherberg, Germany

9 Institute of Environmental Medicine, UNIKA-T, Technische Universität München, Munich, Germany

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BMC Plant Biology 2014, 14:176  doi:10.1186/1471-2229-14-176

Published: 27 June 2014

Abstract

Background

Pollen 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.

Results

Ragweed 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.

Conclusions

The 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.

Keywords:
Ambrosia artemisiifolia; Allergen; Allergy; CO2; Drought; Flavonoids; Pollen; Ragweed; Scanning electron microscopy; Transcriptome